Gaseous product of interaction. Training work in organic chemistry. Acid

When heated, carbonates (all except for alkali metal and ammonium carbonates) decompose to metal oxide and carbon monoxide (IV). CaCO 3 CaO + CO 2

When heated, ammonium carbonate decomposes into ammonia, water and carbon dioxide:

(NH 4) 2 CO 3 2NH 3 + 2H 2 O + CO 2

When heated, bicarbonates transform into carbonates: 2NaHCO 3 Na 2 CO 3 + CO 2 + H 2 O

A qualitative reaction to ions CO 3 2─ and HCO 3 is their interaction with stronger acids, the latter displace carbonic acid from salts, and that decomposes with the release of CO 2

Na 2 CO 3 + 2HCl = 2NaCl + CO 2 + H 2 O NaHCO 3 + HCl = NaCl + CO 2 + H 2 O

When the solutions are mixed, hydrolysis will occur both in the weak acid anion and in the weak base cation: 3Na 2 CO 3 + 2FeCl 3 + 3H 2 O = 2Fe (OH) 3 + 6NaCl + 3CO 2

Silicon. At low temperatures, silicon is chemically inert; at high temperatures, it reacts with both non-metals and some metals. In most cases, silicon is a reducing agent; in reactions with stronger reducing agents (active metals) it acts as an oxidizing agent.

When heated above 400 ° C, silicon interacts with oxygen: Si + O 2 = SiO 2

When interacting with halogens (with fluorine at room temperature), when heated with chlorine, bromine, iodine, silicon halides are formed:

Si + 2Cl 2 = SiCl 4 Si + 2Br 2 = SiBr 4

At temperatures above 600 ° C, it interacts with sulfur: Si + 2S = SiS 2

At a temperature of about 2000 ° C, silicon combines with carbon to form silicon carbide (carborundum): Si + C = SiC

When interacting with active metals, metal silicides are formed: Si + 2Mg = Mg 2 Si

Si + 2Ca = Ca 2 Si Si + 2MgO = Mg 2 Si + 2SiO

Silicides of alkali, alkaline earth metals and magnesium decompose with water, alkalis and dilute acids to form silane:

Mg 2 Si + 4H 2 O = 2Mg (OH) 2 + SiH 4 Mg 2 Si + 4HCl = 2MgCl 2 + SiH 4

2Ca 2 Si + 4NaOH + 10H 2 O = 2Na 2 SiO 3 + 4Ca (OH) 2 + SiH 4

In aqueous solutions of alkalis, silicon dissolves to form silicic acid salts:

Si + 2NaOH + H 2 O = Na 2 SiO 3 + 2H 2

Silicon does not interact with aqueous solutions of acids, but amorphous silicon dissolves in hydrofluoric acid: Si + 6HF = H 2 + 2H 2 (Si (tv) + 4HF (g) = SiF 4 + 2H 2)

Silicon dissolves in a mixture of concentrated nitric and hydrofluoric acids:

3Si + 4HNO 3 + 12HF = 3SiF 4 + 4NO + 8H 2 O

Silicon (IV) oxide. As an acidic oxide, SiO 2, when melted, interacts with solid alkalis, basic oxides and carbonates to form silicic acid salts (silicates):

SiO 2 + 2KOH K 2 SiO 3 + H 2 O (alkali solutions also act on SiO 2)

SiO 2 + CaO CaCO 3 SiO 2 + K 2 CO 3 K 2 SiO 3 + CO 2

Interacts with hydrofluoric acid: SiO 2 + 6HF = H 2 + 2H 2 O

When a mixture of SiO 2 is heated with carbon, silicon carbide is formed: SiO 2 + 3C SiC + 2CO

SiO 2 + 2Mg 2MgO + Si 3SiO 2 + Ca 3 (PO 4) 2 + 5C 3CaSiO 3 + 5CO + 2P

Silane- poisonous colorless gas. In air, silane burns with the formation of SiO 2 and H 2 O, decomposes with water and alkalis with the release of hydrogen: SiH 4 + 2O 2 = SiO 2 + 2H 2 O

SiH 4 + 2H 2 O = SiO 2 + 4H 2 SiH 4 + 2NaOH + H 2 O = Na 2 SiO 3 + 4H 2

Silicon tetrachloride.

SiCl 4 + 3H 2 O = H 2 SiO 3 ↓ + 4HCl SiCl 4 + 2H 2 = Si + 4HCl

1. Gases that are released when coal is heated in concentrated nitric and sulfuric acids were mixed with each other. The reaction products were passed through milk of lime

2. The quicklime was “quenched” with water. A gas was passed into the resulting solution, which was released when sodium bicarbonate was heated, while the formation and subsequent dissolution were observed.

3. The gas formed during the combustion of coke has been in contact with hot coal for a long time. The reaction product was subsequently passed through a bed of iron ore and quicklime.

4. One of the substances formed during the fusion of silicon oxide with magnesium dissolves in alkali. The evolved gas was reacted with sulfur, and the product of their interaction was treated with chlorine.

5. The magnesium silicide was treated with a solution of hydrochloric acid and the evolved gas was burnt. The solid reaction product was mixed with soda ash, the mixture was heated to melt and held for some time. After cooling, the reaction product (used under the name "liquid glass") was dissolved in water and treated with a solution of sulfuric acid.

6. Silicon (IV) chloride was heated in a mixture with hydrogen. The reaction product was mixed with magnesium powder, heated and treated with water, one of the resulting substances ignites spontaneously in air

7. Magnesium silicide was treated with hydrochloric acid solution, the reaction product was burned, the resulting solid was mixed with soda ash and heated to melt. After cooling the melt, it was treated with water and nitric acid was added to the resulting solution.

8. The magnesium powder was mixed with silicon and heated. The reaction product was treated with cold water and the evolved gas was passed through hot water. The formed precipitate was separated, mixed with sodium hydroxide and heated to melting.

9. Silicon was burnt in a chlorine atmosphere. The resulting chloride was treated with water. the precipitate released during this was calcined. Then fused with calcium phosphate and coal.

10. The substance formed during the fusion of magnesium with silicon was treated with water, as a result a colorless gas was formed and evolved. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate, with the formation of two water-insoluble binary substances.

11. The product of the interaction of silicon with chlorine is easily hydrolyzed. When the solid hydrolysis product fusion with both caustic and soda ash, water glass is formed.

12. Carbon was burned in an excess of oxygen, the resulting gas was passed over copper (II) oxide. The resulting substance was fused with sulfur, and the product of this reaction was burned in oxygen.

13. Silicon was burned in oxygen. The reaction product was fused with sodium carbonate, the resulting substance was treated with an excess of hydrochloric acid while heating. The precipitate was filtered off, and silver nitrate solution was added to the filtrate.

14. Silicon was dissolved in concentrated sodium hydroxide solution. Carbon dioxide was passed through the resulting solution. The formed precipitate was filtered off, dried and divided into two parts. The first was dissolved in hydrofluoric acid, the second was fused with magnesium.

1.C + 2H 2 SO 4 (conc.) = CO 2 + 2SO 2 + 2H 2 O C + 4HNO 3 (conc.) = CO 2 + 4NO 2 + 2H 2 O

SO 2 + NO 2 = SO 3 + NO SO 3 + Ca (OH) 2 = CaSO 4 ↓ + H 2 O + CO 2

Ca (OH) 2 = CaCO 3 ↓ + H 2 O

2.CaO + H 2 O = Ca (OH) 2 2NaHCO 3 Na 2 CO 3 + CO 2 + H 2 O

CO 2 + Ca (OH) 2 = CaCO 3 ↓ + H 2 O CaCO 3 + CO 2 + H 2 O = Ca (HCO 3) 2

3.C + O 2 = CO 2 CO 2 + C = 2CO

Fe 2 O 3 + 3CO = 2Fe + 3CO 2 or Fe 3 O 4 + 4CO = 3Fe + 4CO 2

CaO + CO 2 = CaCO 3

4.2C + O 2 = 2CO CO + CuO = Cu + CO 2

Cu + S = CuS 2CuS + 3O 2 = 2CuO + 2SO 2

5.SiO 2 + 2Mg = 2MgO + Si Si + 2NaOH + 2H 2 O = Na 2 SiO 3 + 2H 2

H 2 + S = H 2 S H 2 S + Cl 2 = 2HCl + S ↓

6.Mg 2 Si + 4HCl = 2MgCl 2 + 2SiH 4 SiH 4 + 2O 2 = SiO 2 + 2H 2 O

SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2 Na 2 SiO 3 + H 2 SO 4 = Na 2 SO 4 + H 2 SiO 3 ↓

7.SiCl 4 + 2H 2 = Si + 4HCl Si + 2Mg = Mg 2 Si

Mg 2 Si + 4H 2 O = 2Mg (OH) 2 ↓ + SiH 4 SiH 4 + 2O 2 = SiO 2 ↓ + 2H 2 O

8.Mg 2 Si + 4HCl = 2MgCl 2 + 2SiH 4 SiH 4 + 2O 2 = SiO 2 + 2H 2 O

SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2 Na 2 SiO 3 + 2HNO 3 = 2NaNO 3 + H 2 SiO 3 ↓

9.Si + 2Mg = Mg 2 Si Mg 2 Si + 4H 2 O (hall) = 2Mg (OH) 2 ↓ + SiH 4

SiH 4 + 2H 2 O (horizontal) = SiO 2 + 4H 2 SiO 2 + 2NaOH = Na 2 SiO 3 + H 2 O

10.Si + 2Cl 2 = SiCl 4 SiCl 4 + 3H 2 O = H 2 SiO 3 ↓ + 4HCl

H 2 SiO 3 SiO 2 + H 2 O 3SiO 2 + Ca 3 (PO 4) 2 + 5C 3CaSiO 3 + 5CO + 2P

11.Si + 2Mg = Mg 2 Si Mg 2 Si + 4H 2 O (hall) = 2Mg (OH) 2 ↓ + SiH 4

Mg (OH) 2 + 2HCl = MgCl 2 + 2H 2 O SiH 4 + 8KMnO 4 = 8MnO 2 ↓ + 3SiO 2 ↓ + 8KOH + 2H 2 O

12.Si + 2Cl 2 = SiCl 4 SiCl 4 + 2H 2 O = SiO 2 ↓ + 4HCl

SiO 2 + 2NaOH = Na 2 SiO 3 + H 2 O SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2

13.Si + O 2 = SiO 2 SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2

Na 2 SiO 3 + 2HCl = 2NaCl + SiO 2 ↓ + H 2 O NaCl + AgNO 3 = AgCl ↓ + NaNO 3

14.Si + 2NaOH + 2H 2 O = Na 2 SiO 3 + 2H 2 Na 2 SiO 3 + CO 2 = Na 2 CO 3 + SiO 2 ↓

SiO 2 + 4HF = SiF 4 + 2H 2 O SiO 2 + 2Mg = Si + 2MgO

Nitrogen. Nitrogen compounds.

Nitrogen in the laboratory are obtained by decomposition of ammonium nitrite:

NH 4 NO 2 N 2 + 2H 2 O NaNO 2 + NH 4 Cl N 2 + NaCl + 2H 2 O

Under normal conditions, nitrogen does not react with metals (with the exception of lithium - N 2 interacts with it at room temperature), or with non-metals. When heated, the reactivity of nitrogen increases.

When interacting with metals, metal nitrides are formed:

N 2 + 6 Li = 2Li 3 N N 2 + 6 Na 2Na 3 N

N 2 + 3Mg Mg 3 N 2 N 2 + 2Al (powder) 2AlN

Nitrides of alkali and alkaline earth metals are readily decomposed by water and acid solutions:

Li 3 N + 3H 2 O = 3LiOH + NH 3 Ca 3 N 2 + 6HCl = 3CaCl 2 + 2NH 3

Nitrogen interacts with non-metals only under special conditions - at high temperature, pressure, in the presence of a catalyst or when passing a strong electric discharge:

N 2 + 3H 2 2NH 3 N 2 + O 2 2NO N 2 + 3LiH Li 3 N + NH 3

Ammonia. Ammonia reacts most vigorously with chlorine and bromine, oxides of some metals, and also (when the mixture is ignited or in the presence of a catalyst) with oxygen:

2NH 3 + 3Cl 2 = N 2 + 6HCl 2NH 3 + 3CuO = 3Cu + N 2 + 3H 2 O

4NH 3 + 3O 2 = 2N 2 + 6H 2 O 4NH 3 + 5O 2 4NO + 6H 2 O

Hydrogen peroxide also oxidizes ammonia to nitrogen: 2NH 3 + 3H 2 O 2 = N 2 + 6H 2 O

Due to hydrogen atoms in the oxidation state +1, ammonia can act as an oxidizing agent, for example, in reactions with alkali, alkaline earth metals, magnesium and aluminum:

2NH 3 + 2Na = 2NaNH 2 + H 2 (Na 2 NH, Na 3 N) 2NH 3 + 2Al = 2AlN + 3H 2

The dissolution of ammonia in water is accompanied by chemical interaction with it:

NH 3 + H 2 O ↔ NH 3 ∙ H 2 O ↔ NH 4 + + OH -

When interacting with acids, ammonium salts are formed:

NH 3 + HCl = NH 4 Cl NH 3 + H 2 SO 4 = NH 4 HSO 4 2NH 3 + H 2 SO 4 = (NH 4) 2 SO 4

When ammonia interacts with carbon dioxide, carbamide (urea) is formed:

2NH 3 + CO 2 = (NH 2) 2 CO + H 2 O

Ammonia enters into complexation reactions:

6NH 3 + CuCl 2 = Cl 2 4NH 3 + Cu (OH) 2 = (OH) 2

Ammonium salts. All ammonium salts exhibit the general properties of salts (interact with solutions of acids, alkalis and other salts), and also undergo hydrolysis and decompose when heated:

NH 4 Cl + KOH = KCl + NH 3 + H 2 O (qualitative reaction to NH 4 +)

(NH 4) 2 SO 4 + Ba (NO 3) 2 = 2NH 4 NO 3 + BaSO 4 ↓ NH 4 HS + 3HNO 3 = S + 2NO 2 + NH 4 NO 3 + 2H 2 O

If the salt does not contain an oxidizing anion, then the decomposition proceeds without changing the oxidation state of the nitrogen atom: NH 4 Cl NH 3 + HCl NH 4 HCO 3 NH 3 + CO 2 + H 2 O

(NH 4) 2 SO 4 NH 4 HSO 4 + NH 3 NH 4 HS NH 3 + H 2 S

If the salt contains an oxidizing anion, then the decomposition is accompanied by a change in the oxidation state of the nitrogen atom of the ammonium ion: NH 4 NO 2 N 2 + 2H 2 O NH 4 NO 3 = N 2 O + 2H 2 O (190 - 245 ° C)

2NH 4 NO 3 = 2NO + 4H 2 O (250 - 300 ° C) 2NH 4 NO 3 = 2N 2 + O 2 + 4H 2 O (above 300 ° C)

(NH 4) 2 Cr 2 O 7 Cr 2 O 3 + N 2 + 4H 2 O

Nitrogen oxides. Under normal conditions N 2 O chemically inert, when heated, it exhibits the properties of an oxidizing agent:

N 2 O + H 2 = N 2 + H 2 O N 2 O + Mg = N 2 + MgO

N 2 O + 2Cu = N 2 + Cu 2 O 3N 2 O + 2NH 3 = 4N 2 + 3H 2 O

N 2 O + H 2 O + SO 2 = N 2 + H 2 SO 4

When interacting with strong oxidants, N 2 O can exhibit the properties of a reducing agent:

5N 2 O + 3H 2 SO 4 + 2KMnO 4 = 10NO + 2MnSO 4 + K 2 SO 4 + 3H 2 O

NO poisonous! In the laboratory, they are obtained by the interaction of 30% nitric acid with some metals: 3Cu + 8HNO 3 = 3Cu (NO 3) 2 + 2NO + 4H 2 O

Also, NO can be obtained by the reactions: FeCl 2 + NaNO 3 + 2HCl = FeCl 3 + NaCl + NO + H 2 O

2HNO 3 + 2HI = 2NO + I 2 + 2H 2 O

In air, NO is almost instantly oxidized to NO 2: 2NO + O 2 = 2NO 2

In relation to halogens, NO also exhibits the properties of a reducing agent:

2NO + Cl 2 = 2NOCl NO + O 3 = NO 2 + O 2

In the presence of stronger reducing agents, it exhibits oxidizing properties:

2NO + 2H 2 = N 2 + 2H 2 O 2NO + 2SO 2 = 2SO 3 + N 2

N 2 O 3 Acidic oxide. Nitrous acid anhydride. When interacting with water, it gives nitrous acid: N 2 O 3 + H 2 O ↔ 2HNO 2

When interacting with alkali solutions, nitrites are formed: N 2 O 3 + 2NaOH = 2NaNO 2 + H 2 O

NO 2 Very poisonous! NO 2 is characterized by high chemical activity: it interacts with non-metals (phosphorus, coal, sulfur burn in nitrogen oxide (IV), sulfur oxide (IV) is oxidized to sulfur oxide VI)). In these reactions, NO 2 is an oxidizing agent: 2NO 2 + 2S = N 2 + 2SO 2 2NO 2 + 2C = N 2 + 2CO 2

10NO 2 + 8P = 5N 2 + 4P 2 O 5 NO 2 + SO 2 = SO 3 + NO

Dissolution of NO 2 in water leads to the formation of nitric and nitrous acids:

2NO 2 + H 2 O = HNO 3 + HNO 2

Since nitrous acid is unstable, when NO 2 dissolves in warm water, HNO 3 and NO are formed:

3NO 2 + H 2 O = 2HNO 3 + NO On heating: 4NO 2 + 2H 2 O = 4HNO 3 + O 2

If the dissolution of NO 2 in water is carried out in an excess of oxygen, then only nitric acid is formed:

4NO 2 + 2H 2 O + O 2 = 4HNO 3

When dissolved in alkalis - nitrates and nitrites:

2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 4NO 2 + 2Ca (OH) 2 = Ca (NO 2) 2 + Ca (NO 3) 2 + 2H 2 O

In the presence of oxygen - nitrates: 4NO 2 + 4NaOH + O 2 = 4NaNO 3 + 2H 2 O

N 2 O 5 Acidic oxide. Nitric acid anhydride. Dissolves in water to form nitric acid:

N 2 O 5 + H 2 O = 2HNO 3, in alkalis - with the formation of nitrates: N 2 O 5 + 2NaOH = 2NaNO 3 + H 2 O

HNO 2 Nitrous acid exists only in dilute solutions, when heated, it decomposes: 3HNO 2 ↔ HNO 3 + 2NO + H 2 O

Since the oxidation state of nitrogen in HNO 2 is +3, nitrous acid exhibits both oxidizing and reducing properties:

2HNO 2 + 2HI = 2NO + I 2 + 2H 2 O 5HNO 3 + 2HMnO 4 = 2Mn (NO 3) 2 + HNO 3 + 3H 2 O

HNO 2 + Cl 2 + H 2 O = HNO 3 + 2HCl 2HNO 2 + O 2 = 2HNO 3

HNO 2 + H 2 O 2 = HNO 3 + H 2 O 2HNO 2 + 3H 2 SO 4 + 6FeSO 4 = 3Fe 2 (SO 4) 3 + N 2 + 4H 2 O

HNO 3 Nitric acid when boiling (t boiling = 85 ° C) and with prolonged standing, it partially decomposes:

4HNO 3 4NO 2 + O 2 + 2H 2 O

Nitric acid is highly reactive. The oxidation state of nitrogen in HNO 3 is +5, therefore nitric acid is an oxidizing agent, and a very strong one. Depending on the conditions (nature of the reducing agent, concentration of HNO 3 and temperature), the oxidation state of the nitrogen atom in the reaction products can vary from +4 to −3: NO 2, NO, N 2 O, N 2, NH 4 +

The higher the concentration of nitric acid, the less electrons the NO 3 - anion is inclined to accept.

Interaction with metals. Concentrated HNO 3 does not react with aluminum, chromium and iron in the cold - the acid "passivates" the metals, because a film of oxides is formed on their surface, impermeable to concentrated nitric acid. When heated, the reaction proceeds:

Fe + 6HNO 3 (conc.) Fe (NO 3) 3 + 3NO 2 + 3H 2 O Al + 6HNO 3 (conc.) Al (NO 3) 3 + 3NO 2 + 3H 2 O

Gold and platinum are dissolved in "aqua regia" - a mixture of concentrated nitric and hydrochloric acids in a ratio of 1: 3 (by volume) HNO 3 + 3HCl + Au = AuCl 3 + NO + 2H 2 O

4HNO 3 (conc.) + Cu = Cu (NO 3) 2 + 2NO 2 + 2H 2 O 8HNO 3 (dil.) + 3Cu = 3Cu (NO 3) 2 + 2NO + H 2 O

4HNO 3 (60%) + Zn = Zn (NO 3) 2 + 2NO 2 + 2H 2 O 8HNO 3 (30%) + 3Zn = 3Zn (NO 3) 2 + 2NO + 4H 2 O 10HNO 3 (20%) + 4Zn = 4Zn (NO 3) 2 + 2N 2 O + 5H 2 O 10HNO 3 (3%) + 4Zn = 4Zn (NO 3) 2 + NH 4 NO 3 + 3H 2 O

When interacting with non-metals, HNO 3 is usually reduced to NO or NO 2, non-metals are oxidized to the corresponding acids: 6HNO 3 + S = H 2 SO 4 + 6NO 2 + 2H 2 O 5HNO 3 + P = H 3 PO 4 + 5NO 2 + H 2 O 5HNO 3 + 3P + 2H 2 O = 3H 3 PO 4 + 5NO 4HNO 3 + C = CO 2 + 4NO 2 + 2H 2 O 10HNO 3 + I 2 = 2HIO 3 + 10NO 2 + 4H 2 O

The properties of the oxidizing agent НNO 3 can also show in reactions with complex substances:

6HNO 3 + HI = HIO 3 + 6NO 2 + 3H 2 O 2HNO 3 + SO 2 = H 2 SO 4 + 2NO 2

2HNO 3 + H 2 S = S + 2NO 2 + 2H 2 O 8HNO 3 + CuS = CuSO 4 + 8NO 2 + 4H 2 O

4HNO 3 + FeS = Fe (NO 3) 3 + NO + S + 2H 2 O

Nitrous acid salts nitrites more stable than the acid itself, and they are all poisonous. Since the oxidation state of nitrogen in nitrites is +3, they exhibit both oxidizing and reducing properties:

2KNO 2 + O 2 = 2KNO 3 KNO 2 + H 2 O 2 = KNO 3 + H 2 O

KNO 2 + H 2 O + Br 2 = KNO 3 + 2HBr 5KNO 2 + 3H 2 SO 4 + 2KMnO 4 = 5KNO 3 + 2MnSO 4 + K 2 SO 4 + 3H 2 O

3KNO 2 + 4H 2 SO 4 + K 2 Cr 2 O 7 = 3KNO 3 + Cr 2 (SO 4) 3 + K 2 SO 4 + 4H 2 O

2KNO 2 + 2H 2 SO 4 + 2KI = 2NO + I 2 + 2K 2 SO 4 + 2H 2 O 3KNO 2 + Cr 2 O 3 + KNO 3 = 2K 2 CrO 4 + 4NO

Nitric acid salts - nitrates thermally unstable, and they all decompose into oxygen and a compound, the nature of which depends on the position of the metal (included in the salt) in the series of metal stresses:

1) Salts of alkali and alkaline earth metals (to Mg) decompose to nitrite and oxygen:

2NaNO 3 2NaNO 2 + O 2

2) Salts of heavy metals (from Mg to Cu) - to metal oxide, nitrogen oxide (IV) and oxygen:

2Cu (NO 3) 2 2CuO + 4NO 2 + O

3) Salts of low-activity metals (to the right of Cu) - to metal, nitric oxide (IV) and oxygen

2AgNO 3 2Ag + 2NO 2 + O 2

A mixture of 75% KNO 3, 15% C and 10% S is called "black powder" 2KNO 3 + 3C + S = N 2 + 3CO 2 + K 2 S + Q

1. Two salts contain the same cation. The thermal decay of the first of them resembles a volcanic eruption, with the release of an inactive colorless gas that is part of the atmosphere. When the second salt interacts with a solution of silver nitrate, a white cheesy precipitate is formed, and when it is heated with an alkali solution, a colorless poisonous gas with a pungent odor is released; this gas can also be obtained by the interaction of magnesium nitride with water.

2. Electric discharges were passed over the surface of the caustic soda solution poured into the flask, and the air in the flask turned brown, which disappeared after some time. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. When this mixture is heated, gas is released and only one substance remains.

3. As a result of the thermal decomposition of ammonium dichromate, a gas was obtained, which was passed over heated magnesium. The resulting substance was placed in water. The resulting gas was passed through freshly precipitated copper (II) hydroxide.

4. The gas evolved at the anode during the electrolysis of mercury (II) nitrate was used for the catalytic oxidation of ammonia. The resulting colorless gas instantly reacted with atmospheric oxygen. The resulting brown gas was passed through barite water.

5. Iodine was placed in a test tube with concentrated hot nitric acid. The evolved gas was passed through water in the presence of oxygen. Copper (II) hydroxide was added to the resulting solution. The resulting solution was evaporated and the dry solid residue was calcined.

6. The product of interaction of lithium with nitrogen was treated with water. The resulting gas was passed through a sulfuric acid solution until the termination of chemical reactions. The resulting solution was treated with barium chloride. The solution was filtered and the filtrate was mixed with sodium nitrite solution and heated.

7. A weighed portion of aluminum was dissolved in dilute nitric acid, and a simple substance was isolated. Sodium carbonate was added to the resulting solution until gas evolution completely ceased. The precipitate that formed was filtered off and calcined, the filtrate was evaporated, the resulting solid residue was fused with ammonium chloride. The evolved gas was mixed with ammonia and the resulting mixture was heated.

8. Two salts contain the same cation. The thermal decay of the first of them resembles a volcanic eruption, with the release of an inactive colorless gas that is part of the atmosphere. When the second salt interacts with a solution of silver nitrate, a white cheesy precipitate is formed, and when it is heated with an alkali solution, a colorless poisonous gas with a pungent odor is released; this gas can also be obtained by the interaction of magnesium nitride with water.

9. Electric discharges were passed over the surface of the caustic soda solution poured into the flask, while the air in the flask turned brown, which disappeared after some time. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. When this mixture is heated, gas is released and only one substance remains.

10. A mixture of two colorless, colorless and odorless gases A and B was passed while heating over a catalyst containing iron, and the resulting gas C was neutralized with a solution of hydrobromic acid. The solution was evaporated and the residue was heated with caustic potash, resulting in the evolution of colorless gas B with a pungent odor. When gas B is burned in air, water and gas A are formed.

11. The nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was calcined. The resulting substance was introduced into a solution acidified with sulfuric acid with potassium permanganate, and the solution became discolored. The nitrogen-containing reaction product was placed in a sodium hydroxide solution and zinc dust was added, while a gas with a pungent characteristic odor was released.

12. The nitrogen-hydrogen mixture was heated to a temperature of 500 ° C and passed under high pressure over an iron catalyst. The reaction products were passed through a nitric acid solution until it was neutralized. The resulting solution was carefully evaporated, the solid residue was calcined, and the gas released during this process was passed over copper while heating, resulting in the formation of a black substance.

13. The product of the interaction of nitrogen and lithium was treated with water. The gas evolved as a result of the reaction was mixed with an excess of oxygen and, when heated, passed over a platinum catalyst; the resulting gas mixture had a brown color.

14. A gas mixture of ammonia and a large excess of air was passed while heating over platinum, and after a while the reaction products were absorbed in a sodium hydroxide solution. After evaporation of the solution, a single product was obtained.

15. Through the excess potassium hydroxide solution, a brown gas was passed in the presence of a large excess of air. Magnesium shavings were added to the resulting solution and heated; the released gas neutralized nitric acid. The resulting solution was carefully evaporated, and the solid product was calcined.

16. Copper (I) oxide was treated with concentrated nitric acid, the solution was carefully evaporated and the solid residue was calcined. The gaseous reaction products were passed through a large amount of water and magnesium chips were added to the resulting solution, resulting in the release of a gas used in medicine.

17. Magnesium nitride was treated with excess water. When the released gas is passed through bromine water or through a neutral solution of potassium permanganate, and when it is burned, the same gaseous product is formed.

18. One of the products of the interaction of ammonia with bromine - a gas that is part of the atmosphere, was mixed with hydrogen and heated in the presence of platinum. The resulting gas mixture was passed through a hydrochloric acid solution and potassium nitrite was added to the resulting solution with slight heating.

19. Magnesium was heated in a vessel filled with gaseous ammonia. The resulting substance was dissolved in a concentrated solution of hydrobromic acid, the solution was evaporated and the residue was heated until an odor appeared, after which an alkali solution was added.

20. A mixture of nitrogen and hydrogen was passed sequentially over heated platinum and through a sulfuric acid solution. Barium chloride was added to the solution and, after separating the precipitated sediment, milk of lime was added and heated.

21. Ammonia was mixed with a large excess of air, heated in the presence of platinum and after a while absorbed in water. Copper shavings added to the resulting solution dissolve with the release of brown gas.

22. When an orange-colored substance is heated, it decomposes; Decomposition products include a colorless gas and a green solid. The released gas reacts with lithium even when heated slightly. The product of the last reaction interacts with water, while a gas with a pungent odor is released, which can reduce metals, for example, copper from their oxides.

23. Metallic calcium was calcined under nitrogen atmosphere. The reaction product was treated with water, and the gas released during this process was passed into a solution of chromium (III) nitrate. The gray-green precipitate formed during the process was treated with an alkaline solution of hydrogen peroxide.

24. A mixture of potassium nitrite and ammonium chloride powders was dissolved in water and the solution was heated carefully. The released gas reacted with magnesium. The reaction product was added to an excess of hydrochloric acid solution, and no gas evolution was observed. the obtained magnesium salt in solution was treated with sodium carbonate.

25. Copper was dissolved in concentrated nitric acid. An excess of ammonia solution was added to the resulting solution, first the formation of a precipitate was observed, and then its complete dissolution. The resulting solution was treated with an excess of hydrochloric acid.

26. Magnesium was dissolved in dilute nitric acid and no gas evolution was observed. The resulting solution was treated with an excess of potassium hydroxide solution with heating. The gas released during this process was burned in oxygen.

27. Potassium nitrite was heated with powdered lead until the reaction was terminated. The product mixture was treated with water, and then the resulting solution was filtered. The filtrate was acidified with sulfuric acid and treated with potassium iodide. The separated simple substance was heated with concentrated nitric acid. In the atmosphere of the resulting brown gas, red phosphorus was burned.

28. The gas formed by the interaction of nitrogen and hydrogen was divided into two parts. The first was passed over red-hot copper (II) oxide, the second was burned in oxygen in the presence of a catalyst. The resulting gas in an excess of oxygen was turned into a brown gas.

29. Diluted nitric acid reacted with magnesium to give off a colorless gas. In its atmosphere, graphite was burned to form a simple and complex substance. a simple substance reacted with calcium when heated, and a complex reacted with an excess of sodium hydroxide solution.

30. Ammonia was absorbed in nitric acid, the resulting salt was heated until only two oxides were formed. One of them reacted with sodium, and the second reacted with copper at a high temperature.

31. Nitric oxide (II) was additionally oxidized with oxygen. The reaction product was absorbed with a potassium hydroxide solution, oxygen was passed through the resulting solution until only one salt was formed in it.

32. Calcium was burned in nitrogen atmosphere. The resulting substance was decomposed with boiling water. The released gas was burned in oxygen in the presence of a catalyst, and a solution of hydrochloric acid was added to the suspension.

33. Nitrogen, when heated on the catalyst, reacted with hydrogen. The resulting gas was absorbed with a nitric acid solution, evaporated to dryness, and the resulting crystalline substance was divided into two parts. The first was decomposed at a temperature of 190-240 ° C, while only one gas and water vapor was formed. The second part was heated with concentrated sodium hydroxide solution.

1) (NH 4) 2 Cr 2 O 7 N 2 + Cr 2 O 3 + 4H 2 O NH 4 Cl + AgNO 3 = AgCl ↓ + NH 4 NO 3

NH 4 Cl + NaOH = NaCl + NH 3 + H 2 O Mg 3 N 2 + 6H 2 O = 3Mg (OH) 2 ↓ + 2NH 3

2) N 2 + O 2 2NO 2NO + O 2 = 2NO 2

NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 2NaNO 3 2NaNO 2 + O 2

3) (NH 4) 2 Cr 2 O 7 N 2 + Cr 2 O 3 + 4H 2 O 3Mg + N 2 = Mg 3 N 2

Mg 3 N 2 + 6H 2 O = 3Mg (OH) 2 ↓ + 2NH 3 4NH 3 + Cu (OH) 2 = (OH) 2

4) 2Hg (NO 3) 2 + 2H 2 O 2Hg + O 2 + 4HNO 3 4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2 4NO 2 + 2Ba (OH) 2 = Ba (NO 3) 2 + Ba (NO 2) 2 + 2H 2 O

5) I 2 + 10HNO 3 = 2HIO 3 + 10NO 2 + 4H 2 O 4NO 2 + O 2 + 2H 2 O = 4HNO 3

2HNO 3 + Cu (OH) 2 = Cu (NO 3) 2 + 2H 2 O 2Cu (NO 3) 2 2CuO + O 2 + 4NO 2

6) 6Li + N 2 = 2Li 3 N Li 3 N + 3H 2 O = 3LiOH + NH 3

2NH 3 + H 2 SO 4 = (NH 4) 2 SO 4 (NH 4) 2 SO 4 + BaCl 2 = BaSO 4 + 2NH 4 Cl

NH 4 Cl + NaNO 2 N 2 + NaCl + 2H 2 O

7) 10Al + 36HNO 3 = 10Al (NO 3) 3 + 3N 2 + 18H 2 O 2Al (NO 3) 3 + 3Na 2 CO 3 + 3H 2 O = 2Al (OH) 3 ↓ + 3CO 2 + 6NaNO 3

2Al (OH) 3 Al 2 O 3 + 3H 2 O NaNO 3 + NH 4 Cl N 2 O + NaCl + 2H 2 O 3N 2 O + 2NH 3 = 4N 2 + 3H 2 O

8) (NH 4) 2 Cr 2 O 7 N 2 + Cr 2 O 3 + 4H 2 O NH 4 Cl + AgNO 3 = AgCl ↓ + NH 4 NO 3

NH 4 Cl + NaOH = NaCl + NH 3 + H 2 O Mg 3 N 2 + 6H 2 O = 2NH 3 + 3Mg (OH) 2 ↓

9) N 2 + O 2 2NO 2NO + O 2 = 2NO 2

2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 2NaNO 3 2NaNO 2 + O 2

10) N 2 + 3H 2 = 2NH 3 NH 3 + HBr = NH 4 Br

NH 4 Br + KOH = KBr + H 2 O + NH 3 4NH 3 + 3O 2 = 2N 2 + 6H 2 O

11) HNO 3 + NaHCO 3 = NaNO 3 + H 2 O + CO 2 2NaNO 3 2NaNO 2 + O 2

5NaNO 2 + 2KMnO 4 + 3H 2 SO 4 = 5NaNO 3 + K 2 SO 4 + 2MnSO 4 + 3H 2 O

NaNO 3 + 4Zn + 7NaOH + 6H 2 O = NH 3 + 4Na 2

12) N 2 + 3H 2 ↔ 2NH 3 NH 3 + HNO 3 = NH 4 NO 3

NH 4 NO 3 N 2 O + 2H 2 O N 2 O + Cu = CuO + N 2

13) N 2 + 6Li = 2Li 3 N Li 3 N + 3H 2 O = 3LiOH + NH 3

4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2

14) 4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2

2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 2NaNO 2 + O 2 = 2NaNO 3

15) 2NO 2 + O 2 + 2KOH = 2KNO 3 + H 2 O KNO 3 + 4Mg + 6H 2 O = NH 3 + 4Mg (OH) 2 ↓ + KOH

NH 3 + HNO 3 = NH 4 NO 3 NH 4 NO 3 N 2 O + 2H 2 O

16) Cu 2 O + 6HNO 3 = 2Cu (NO 3) 2 + 2NO 2 + 3H 2 O 2Cu (NO 3) 2 2CuO + 4NO 2 + O 2

4NO 2 + O 2 + 2H 2 O = 4HNO 3 4Mg + 10HNO 3 (dil.) = 4Mg (NO 3) 2 + N 2 O + 5H 2 O

or 4Mg + 10HNO 3 (very dil.) = 4Mg (NO 3) 2 + NH 4 NO 3 + 3H 2 O

17) Mg 3 N 2 + 6H 2 O = 3Mg (OH) 2 ↓ + 2NH 3 2NH 3 + 3Br 2 = N 2 + 6HBr or

2KMnO 4 + 2NH 3 = 2MnO 2 + N 2 + 3KOH + 3H 2 O 4NH 3 + 3O 2 = 2N 2 + 6H 2 O

18) 2NH 3 + 3Br 2 = N 2 + 6HBr or 8NH 3 + 3Br 2 = N 2 + 6NH 4 Br

N 2 + 3H 2 ↔ 2NH 3 NH 3 + HCl = NH 4 Cl

19) 2NH 3 + 3Mg = Mg 3 N 2 + 3H 2 Mg 3 N 2 + 8HBr = 3MgBr 2 + 2NH 4 Br

NH 4 Br NH 3 + HBr MgBr 2 + 2NaOH = Mg (OH) 2 ↓ + 2NaBr

20) N 2 + 3H 2 = 2NH 3 2NH 3 + H 2 SO 4 = (NH 4) 2 SO 4

(NH 4) 2 SO 4 + BaCl 2 = 2NH 4 Cl + BaSO 4 ↓ 2NH 4 Cl + Ca (OH) 2 = CaCl 2 + 2NH 3 + 3H 2 O

21) 4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2

4NO 2 + O 2 + 2H 2 O = 4HNO 3 Cu + 4HNO 3 (conc

Alkali metals react easily with non-metals:

2K + I 2 = 2KI

2Na + H 2 = 2NaH

6Li + N 2 = 2Li 3 N (the reaction proceeds already at room temperature)

2Na + S = Na 2 S

2Na + 2C = Na 2 C 2

In reactions with oxygen, each alkali metal shows its individuality: when burning in air, lithium forms an oxide, sodium - peroxide, potassium - superoxide.

4Li + O 2 = 2Li 2 O

2Na + O 2 = Na 2 O 2

K + O 2 = KO 2

Obtaining sodium oxide:

10Na + 2NaNO 3 = 6Na 2 O + N 2

2Na + Na 2 O 2 = 2Na 2 O

2Na + 2NaOH = 2Na 2 O + H 2

Interaction with water leads to the formation of alkali and hydrogen.

2Na + 2H 2 O = 2NaOH + H 2

Interaction with acids:

2Na + 2HCl = 2NaCl + H 2

8Na + 5H 2 SO 4 (conc.) = 4Na 2 SO 4 + H 2 S + 4H 2 O

2Li + 3H 2 SO 4 (conc.) = 2LiHSO 4 + SO 2 + 2H 2 O

8Na + 10HNO 3 = 8NaNO 3 + NH 4 NO 3 + 3H 2 O

When interacting with ammonia, amides and hydrogen are formed:

2Li + 2NH 3 = 2LiNH 2 + H 2

Interaction with organic compounds:

H ─ C ≡ C ─ H + 2Na → Na ─ C≡C ─ Na + H 2

2CH 3 Cl + 2Na → C 2 H 6 + 2NaCl

2C 6 H 5 OH + 2Na → 2C 6 H 5 ONa + H 2

2CH 3 OH + 2Na → 2 CH 3 ONa + H 2

2CH 3 COOH + 2Na → 2CH 3 COOONa + H 2

A qualitative reaction to alkali metals is the coloring of the flame with their cations. Li + ion colors the flame in carmine-red color, Na + ion - in yellow, K + - in violet

Alkali metal compounds

Oxides.

Alkali metal oxides are typical basic oxides. Reacts with acidic and amphoteric oxides, acids, water.

3Na 2 O + P 2 O 5 = 2Na 3 PO 4

Na 2 O + Al 2 O 3 = 2NaAlO 2

Na 2 O + 2HCl = 2NaCl + H 2 O

Na 2 O + 2H + = 2Na + + H 2 O

Na 2 O + H 2 O = 2NaOH

Peroxides.

2Na 2 O 2 + CO 2 = 2Na 2 CO 3 + O 2

Na 2 O 2 + CO = Na 2 CO 3

Na 2 O 2 + SO 2 = Na 2 SO 4

2Na 2 O + O 2 = 2Na 2 O 2

Na 2 O + NO + NO 2 = 2NaNO 2

2Na 2 O 2 = 2Na 2 O + O 2

Na 2 O 2 + 2H 2 O (cold) = 2NaOH + H 2 O 2

2Na 2 O 2 + 2H 2 O (hot) = 4NaOH + O 2

Na 2 O 2 + 2HCl = 2NaCl + H 2 O 2

2Na 2 O 2 + 2H 2 SO 4 (decompression) = 2Na 2 SO 4 + 2H 2 O + O 2

2Na 2 O 2 + S = Na 2 SO 3 + Na 2 O

5Na 2 O 2 + 8H 2 SO 4 + 2KMnO 4 = 5O 2 + 2MnSO 4 + 8H 2 O + 5Na 2 SO 4 + K 2 SO 4

Na 2 O 2 + 2H 2 SO 4 + 2NaI = I 2 + 2Na 2 SO 4 + 2H 2 O

Na 2 O 2 + 2H 2 SO 4 + 2FeSO 4 = Fe 2 (SO 4) 3 + Na 2 SO 4 + 2H 2 O

3Na 2 O 2 + 2Na 3 = 2Na 2 CrO 4 + 8NaOH + 2H 2 O

Bases (alkalis).

2NaOH (excess) + CO 2 = Na 2 CO 3 + H 2 O

NaOH + CO 2 (excess) = NaHCO 3

SO 2 + 2NaOH (excess) = Na 2 SO 3 + H 2 O

SiO 2 + 2NaOH Na 2 SiO 3 + H 2 O

2NaOH + Al 2 O 3 2NaAlO 2 + H 2 O

2NaOH + Al 2 O 3 + 3H 2 O = 2Na

NaOH + Al (OH) 3 = Na

2NaOH + 2Al + 6Н 2 О = 2Na + 3Н 2

2KOH + 2NO 2 + O 2 = 2KNO 3 + H 2 O

KOH + KHCO 3 = K 2 CO 3 + H 2 O

2NaOH + Si + H 2 O = Na 2 SiO 3 + H 2

3KOH + P 4 + 3H 2 O = 3KH 2 PO 2 + PH 3

2KOH (cold) + Cl 2 = KClO + KCl + H 2 O

6KOH (hot) + 3Cl 2 = KClO 3 + 5KCl + 3H 2 O

6NaOH + 3S = 2Na 2 S + Na 2 SO 3 + 3H 2 O

2NaNO 3 2NaNO 2 + O 2

NaHCO 3 + HNO 3 = NaNO 3 + CO 2 + H 2 O

NaI → Na + + I -

at the cathode: 2H 2 O + 2e → H 2 + 2OH - 1

at the anode: 2I - - 2e → I 2 1

2H 2 O + 2I - H 2 + 2OH - + I 2

2H 2 O + 2NaI H 2 + 2NaOH + I 2

2NaCl 2Na + Cl 2

at the cathode at the anode

2Na 2 HPO 4 Na 4 P 2 O 7 + H 2 O

KNO 3 + 4Mg + 6H 2 O = NH 3 + 4Mg (OH) 2 + KOH

4KClO 3 KCl + 3KClO 4

2KClO 3 2KCl + 3O 2

KClO 3 + 6HCl = KCl + 3Cl 2 + 3H 2 O

Na 2 SO 3 + S = Na 2 S 2 O 3

Na 2 S 2 O 3 + H 2 SO 4 = Na 2 SO 4 + S ↓ + SO 2 + H 2 O

2NaI + Br 2 = 2NaBr + I 2

2NaBr + Cl 2 = 2NaCl + Br 2

I A group.

1. Electric discharges were passed over the surface of the caustic soda solution poured into the flask, while the air in the flask turned brown, which disappears after a while. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. When this mixture is heated, gas is released and only one substance remains. Write down the equations for the reactions described.

2. The substance released at the cathode during the electrolysis of the sodium chloride melt was burned in oxygen. The resulting product was placed in a gas meter filled with carbon dioxide. The resulting substance was added to the ammonium chloride solution and the solution was heated. Write down the equations for the reactions described.

3) The nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was calcined. The resulting substance was introduced into a solution of potassium permanganate acidified with sulfuric acid, and the solution became discolored. The nitrogen-containing reaction product was placed in a sodium hydroxide solution and zinc dust was added, while a gas with a pungent odor was released. Write down the equations for the reactions described.

4) The substance obtained at the anode during the electrolysis of a sodium iodide solution with inert electrodes was introduced into a reaction with potassium. The reaction product was heated with concentrated sulfuric acid, and the evolved gas was passed through a hot potassium chromate solution. Write the equations of the described reactions

5) The substance obtained at the cathode during the electrolysis of sodium chloride melt was burned in oxygen. The obtained product was sequentially treated with sulfur dioxide and barium hydroxide solution. Write the equations of the described reactions

6) White phosphorus dissolves in a solution of caustic potassium with the release of a gas with a garlic odor, which spontaneously ignites in air. The solid product of the combustion reaction reacted with sodium hydroxide in such a ratio that the resulting white substance contains one hydrogen atom; when the latter is ignited, sodium pyrophosphate is formed. Write the equations of the described reactions

7) Unknown metal burned in oxygen. The reaction product, interacts with carbon dioxide, forms two substances: a solid, which interacts with a hydrochloric acid solution with the release of carbon dioxide, and a gaseous simple substance that supports combustion. Write down the equations for the reactions described.

8) A brown gas was passed through an excess of potassium hydroxide solution in the presence of a large excess of air. Magnesium shavings were added to the resulting solution and heated, and nitric acid was neutralized with the released gas. The resulting solution was carefully evaporated, and the solid product was calcined. Write down the equations for the reactions described.

9) During the thermal decomposition of salt A in the presence of manganese dioxide, a binary salt B and a gas that supports combustion and is part of the air were formed; when this salt is heated without a catalyst, salt B and a salt of a higher oxygen-containing acid are formed. When salt A interacts with hydrochloric acid, a yellow-green gas (a simple substance) is released and salt B is formed. Salt B colors the flame purple; when it interacts with a solution of silver nitrate, a white precipitate forms. Write down the equations for the reactions described.

10) Copper shavings were added to heated concentrated sulfuric acid, and the released gas was passed through a sodium hydroxide solution (excess). The reaction product was isolated, dissolved in water, and heated with sulfur, which was dissolved as a result of the reaction. Dilute sulfuric acid was added to the resulting solution. Write down the equations for the reactions described.

11) Table salt was treated with concentrated sulfuric acid. The resulting salt was treated with sodium hydroxide. The resulting product was calcined with an excess of coal. The gas evolved during this reacted in the presence of a chlorine catalyst. Write down the equations for the reactions described.

12) Sodium reacted with hydrogen. The reaction product was dissolved in water, while a gas was formed that reacted with chlorine, and the resulting solution, when heated, reacted with chlorine to form a mixture of two salts. Write down the equations for the reactions described.

13) Sodium was burned in an excess of oxygen, the resulting crystalline substance was placed in a glass tube and carbon dioxide was passed through it. The gas exiting the tube was collected and phosphorus was burned in its atmosphere. The resulting substance was neutralized with an excess of sodium hydroxide solution. Write down the equations for the reactions described.

14) To the solution obtained as a result of the interaction of sodium peroxide with water upon heating, a solution of hydrochloric acid was added until the end of the reaction. The solution of the formed salt was subjected to electrolysis with inert electrodes. The gas formed as a result of electrolysis at the anode was passed through a suspension of calcium hydroxide. Write down the equations for the reactions described.

15) Sulfur dioxide was passed through the sodium hydroxide solution until a medium salt was formed. An aqueous solution of potassium permanganate was added to the resulting solution. The formed precipitate was separated and acted on with hydrochloric acid. The evolved gas was passed through a cold potassium hydroxide solution. Write down the equations for the reactions described.

16) A mixture of silicon oxide (IV) and metallic magnesium was calcined. The simple substance obtained as a result of the reaction was treated with a concentrated solution of sodium hydroxide. The evolved gas was passed over heated sodium. The resulting substance was placed in water. Write down the equations for the reactions described.

17) The product of the interaction of lithium with nitrogen was treated with water. The resulting gas was passed through a sulfuric acid solution until the termination of chemical reactions. The resulting solution was treated with a solution of barium chloride. The solution was filtered and the filtrate was mixed with sodium nitrate solution and heated. Write down the equations for the reactions described.

18) Sodium was heated in a hydrogen atmosphere. On adding water to the obtained substance, gas evolution and the formation of a clear solution were observed. A brown gas was passed through this solution, which was obtained as a result of the interaction of copper with a concentrated solution of nitric acid. Write down the equations for the reactions described.

19) Sodium hydrogen carbonate was calcined. The resulting salt was dissolved in water and mixed with an aluminum solution, as a result of which a precipitate formed and a colorless gas evolved. The precipitate was treated with an excess of nitric acid solution, and the gas was passed through a potassium silicate solution. Write down the equations for the reactions described.

20) Sodium was fused with sulfur. The resulting compound was treated with hydrochloric acid, the released gas completely reacted with sulfur oxide (IV). The resulting material was treated with concentrated nitric acid. Write down the equations for the reactions described.

21) Sodium was burned in excess of oxygen. The resulting substance was treated with water. The resulting mixture was boiled, after which chlorine was added to the hot solution. Write down the equations for the reactions described.

22) Potassium was heated under nitrogen atmosphere. The resulting substance was treated with an excess of hydrochloric acid, after which a suspension of calcium hydroxide was added to the resulting mixture of salts and heated. The resulting gas was passed through a red-hot oxide of copper (II). Write down the equations of the described reactions.

23) Potassium was burned in a chlorine atmosphere, the resulting salt was treated with an excess of an aqueous solution of silver nitrate. The formed precipitate was filtered off, the filtrate was evaporated and heated carefully. The resulting salt was treated with an aqueous solution of bromine. Write down the equations for the reactions described.

24) Lithium has reacted with hydrogen. The reaction product was dissolved in water, while a gas was formed that reacted with bromine, and the resulting solution, when heated, reacted with chlorine to form a mixture of two salts. Write down the equations for the reactions described.

25) Sodium was burned in air. The resulting solid absorbs carbon dioxide with the evolution of oxygen and salt. The latter salt was dissolved in hydrochloric acid, and a solution of silver nitrate was added to the resulting solution. This resulted in a white precipitate. Write down the equations for the reactions described.

26) Oxygen was exposed to an electric discharge in an ozonizer. The resulting gas was passed through an aqueous solution of potassium iodide, while a new colorless and odorless gas was released, supporting combustion and respiration. In an atmosphere of the latter gas, sodium was burned, and the resulting solid was reacted with carbon dioxide. Write down the equations for the reactions described.

I A group.

1.N 2 + O 2 2NO

2NO + O 2 = 2NO 2

2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O

2NaNO 3 2NaNO 2 + O 2

2.2NaCl 2Na + Cl 2

at the cathode at the anode

2Na + O 2 = Na 2 O 2

2Na 2 O 2 + 2CO 2 = 2Na 2 CO 3 + O 2

Na 2 CO 3 + 2NH 4 Cl = 2NaCl + CO 2 + 2NH 3 + H 2 O

3. NaHCO 3 + HNO 3 = NaNO 3 + CO 2 + H 2 O

2NaNO 3 2NaNO 2 + O 2

5NaNO 2 + 2KMnO 4 + 3H 2 SO 4 = 5NaNO 3 + 2MnSO 4 + K 2 SO 4 + 3H 2 O

NaNO 3 + 4Zn + 7NaOH + 6H 2 O = 4Na 2 + NH 3

4.2H 2 O + 2NaI H 2 + 2NaOH + I 2

2K + I 2 = 2KI

8KI + 5H 2 SO 4 (conc.) = 4K 2 SO 4 + H 2 S + 4I 2 + 4H 2 O

3H 2 S + 2K 2 CrO 4 + 2H 2 O = 2Cr (OH) 3 ↓ + 3S ↓ + 4KOH

5.2NaCl 2Na + Cl 2

at the cathode at the anode

2Na + O 2 = Na 2 O 2

Na 2 O 2 + SO 2 = Na 2 SO 4

Na 2 SO 4 + Ba (OH) 2 = BaSO 4 ↓ + 2NaOH

6.P 4 + 3KOH + 3H 2 O = 3KH 2 PO 2 + PH 3

2PH 3 + 4O 2 = P 2 O 5 + 3H 2 O

P 2 O 5 + 4NaOH = 2Na 2 HPO 4 + H 2 O

Transcript

1 Tasks 1. The solution obtained by the interaction of copper with concentrated nitric acid was evaporated and the precipitate was calcined. The gaseous products of the decomposition reaction are completely absorbed in water, and hydrogen was passed over the solid residue. Write equations 2. A simple substance obtained by heating calcium phosphate with coke and silicon oxide was fused with metallic calcium. The reaction product was treated with water, and the evolved gas was collected and passed through a hydrochloric acid solution. Write down the equations 3. The precipitate obtained by the interaction of solutions of iron (III) chloride and silver nitrate was filtered off. The filtrate was treated with a potassium hydroxide solution. The resulting brown precipitate was separated and calcined. The resulting substance, when heated, reacts with aluminum with the release of heat and light. Write down equations 4. The substance obtained at the cathode during the electrolysis of sodium chloride melt was burned in oxygen. The resulting product was sequentially treated with sulfur dioxide and barium hydroxide solution. Write down equations 5. The decomposition products of ammonium chloride were sequentially passed through a heated tube containing copper (II) oxide, and then through a bottle with phosphorus (V) oxide. Write the equations 6. A solution of hydrochloric acid was poured into the water-insoluble white salt, which occurs in nature in the form of a mineral widely used in construction and architecture, as a result, the salt dissolved and gas was released, when passed through lime water, a white precipitate formed; the precipitate dissolved upon further gas passage. When the resulting solution is boiled, a precipitate forms. Write down equations 7. The substance obtained at the anode during the electrolysis of sodium iodide solution with inert electrodes reacted with hydrogen sulfide. The resulting solid was fused with aluminum and the product was dissolved in water. Write the equations 8. The gas released during the interaction of hydrogen chloride with potassium permanganate reacts with iron. The reaction product was dissolved in water, and sodium sulfide was added thereto. The lighter of the formed insoluble substances was separated and reacted with hot concentrated nitric acid. Write down the equations 9. Chromium (III) sulfide was treated with water, while gas evolved and an insoluble substance remained. A sodium hydroxide solution was added to this substance and chlorine gas was passed through, while the solution acquired a yellow color. The solution was acidified with sulfuric acid; as a result, the color changed to orange; gas evolved during the treatment of sulfide with water was passed through the resulting solution, and the color of the solution changed to green. Write equations

2 10. Obtaining a black-and-white image when photographing is based on the decomposition of a salt of an unknown metal under the action of light. When this metal dissolves in dilute nitric acid, a colorless gas is released, which in air quickly changes its color to brown, and forms a salt that interacts with sodium bromide to form a yellowish curdled precipitate. The anion in the salt used in photography is the anion of an acid that forms simultaneously with sulfuric acid, when bromine water and sulfur dioxide react. Write down equations 11. Sodium hydroxide solution was added dropwise to the solution obtained by the interaction of aluminum with dilute sulfuric acid until a precipitate was formed. The formed white precipitate was filtered off and calcined. The resulting material was fused with sodium carbonate. Write down equations 12. A constant electric current was passed through a solution of copper (II) chloride using graphite electrodes. The electrolysis product released at the cathode was dissolved in concentrated nitric acid. The resulting gas was collected and passed through a sodium hydroxide solution. The gaseous electrolysis product released at the anode was passed through a hot sodium hydroxide solution. Write down equations 13. A simple substance obtained by heating a mixture of calcium phosphate with coke and silicon oxide (IV) dissolves in a concentrated solution of caustic potassium. The evolved gaseous substance was burned, the combustion products were passed through water, and silver nitrate was added to the resulting solution. Make the equations of four 14. The offensive liquid formed by the interaction of hydrobromic acid with potassium permanganate was separated and heated with iron shavings. The reaction product was dissolved in water, and a cesium hydroxide solution was added thereto. The formed precipitate was filtered off and calcined. Write down the equations 15. Electric discharges were passed over the surface of the caustic soda solution, while the air turned brown, and the color disappeared after a while. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. Keeping a mixture of salts in air leads to the formation of one substance. Write equations 16. Calcium was dissolved in water. When passing through the resulting solution of sulfur dioxide, a white precipitate is formed, which dissolves when passing an excess of gas. Adding alkali to the resulting solution leads to the formation of a white precipitate. Write the equations 17. When a simple yellow substance is burned in air, a gas with a pungent odor is formed. This gas is also released when some metal containing iron is roasted in air. When diluted sulfuric acid acts on a substance consisting of the same elements as a mineral, but in a different ratio, a gas is released with a characteristic

3 the smell of rotten eggs. When the released gases interact with each other, an initial simple substance is formed. Write the equations 18. The gaseous product of the interaction of dry sodium chloride with concentrated sulfuric acid was reacted with a solution of potassium permanganate. The evolved gas was passed through a sodium sulfide solution. The precipitated yellow precipitate is dissolved in a concentrated solution of sodium hydroxide. Write down equations 19. The gas formed by passing hydrogen chloride through a hot potassium chromate solution interacts with iron. The reaction product was dissolved in water, and sodium sulfide was added thereto. The lighter of the formed insoluble substances was separated and reacted with concentrated sulfuric acid when heated. Write equations 20. Two salts contain the same cation. The thermal decay of the first of them resembles a volcanic eruption, with the release of an inactive colorless gas that is part of the atmosphere. When the second salt interacts with a solution of silver nitrate, a white cheesy precipitate is formed, and when it is heated with an alkali solution, a colorless poisonous gas with a pungent odor is released; this gas can also be obtained by the interaction of magnesium nitride with water. Write the equations described 21. To the aluminum sulfate solution was added an excess of sodium hydroxide solution. Hydrochloric acid was added to the resulting solution in small portions, while the formation of a bulk white precipitate was observed, which dissolved upon further addition of acid. Sodium carbonate solution was poured into the resulting solution. Write the equations 22. Electric discharges were passed over the surface of the caustic soda solution poured into the flask, while the air in the flask turned brown, which disappeared after some time. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. When this mixture is heated, gas is released and only one substance remains. Write the equations described 23. Zinc oxide was dissolved in a solution of hydrochloric acid and the solution was neutralized by adding sodium hydroxide. The separated white gelatinous substance was separated and treated with an excess of alkali solution, while the precipitate was completely dissolved. Neutralization of the resulting solution with an acid, for example, nitric acid, leads to the re-formation of a gelatinous precipitate. Write the equations 24. The substance obtained at the cathode during the electrolysis of molten copper (II) chloride reacts with sulfur. The resulting product was treated with concentrated nitric acid and the evolved gas was passed through a barium hydroxide solution. Write equations

4 25. A mixture of calcium orthophosphate, coke and sand was heated in an electric furnace. One of the products of this reaction can spontaneously ignite in air. The solid combustion product of this substance was dissolved in water when heated, and gaseous ammonia was passed through the resulting solution. Write down the equations 26. The substance obtained at the cathode during the electrolysis of a solution of iron (II) chloride was fused with sulfur and the product of this reaction was fired. The resulting gas was passed through a barium hydroxide solution. Write down the equations 27. Copper wire was introduced into the heated concentrated sulfuric acid and the evolved gas was passed through an excess of sodium hydroxide solution. The solution was carefully evaporated, the solid residue was dissolved in water and heated with powdered sulfur. Unreacted sulfur was separated by filtration and sulfuric acid was added to the solution, while the formation of a precipitate and the evolution of gas with a pungent odor were observed. Write the equations 28. After a short heating of an unknown powdery substance of orange color, a spontaneous reaction begins, which is accompanied by a color change to green, the release of gas and sparks. The solid residue was mixed with caustic potassium and heated, the resulting substance was introduced into a dilute solution of hydrochloric acid, and a green precipitate was formed, which dissolves in an excess of acid. Write equations 29. Two salts color the flame purple. One of them is colorless, and when it is slightly heated with concentrated sulfuric acid, the liquid is distilled off, in which copper dissolves; the last transformation is accompanied by the evolution of brown gas. When the second salt of the sulfuric acid solution is added to the solution, the yellow color of the solution changes to orange, and when the resulting solution is neutralized with alkali, the original color is restored. Write the equations 30. The iron (III) chloride solution was electrolyzed with graphite electrodes. The brown precipitate formed as a by-product of electrolysis was filtered off and calcined. The substance formed at the cathode was dissolved in concentrated nitric acid with heating. The product released at the anode was passed through a cold potassium hydroxide solution. Write the equations described 31. The gas released during the interaction of hydrogen chloride with berthollet's salt was introduced into the reaction with aluminum. The reaction product was dissolved in water and sodium hydroxide was added until the precipitation ceased, which was separated and calcined. Write equations 32. The unknown salt is colorless and turns the flame yellow. With a slight heating of this salt with concentrated sulfuric acid, the liquid is distilled off, in

5 which dissolves copper; the last transformation is accompanied by the evolution of brown gas and the formation of a copper salt. During the thermal decomposition of both salts, oxygen is one of the decomposition products. Write the equations 33. The substance obtained at the anode during the electrolysis of sodium iodide melt with inert electrodes was isolated and introduced into interaction with hydrogen sulfide. The gaseous product of the last reaction was dissolved in water and ferric chloride was added to the resulting solution. The formed precipitate was filtered off and treated with hot sodium hydroxide solution. Write the equations 34. The gases that are released when coal is heated in concentrated nitric and sulfuric acids are mixed with each other. The reaction products were passed through milk of lime. Write the equations 35. A mixture of iron powder and a solid product obtained by the interaction of sulfur dioxide and hydrogen sulfide was heated without access to air. The resulting product was calcined in air. The resulting solid reacts with aluminum to generate a large amount of heat. Write the equations 36. A black substance was obtained by calcining the precipitate formed by the interaction of solutions of sodium hydroxide and copper (II) sulfate. When this substance is heated with coal, a red metal is obtained, which dissolves in concentrated sulfuric acid. Write the equations 37. A simple substance, a mixture of which with berthollet's salt is used in matches and ignites upon friction, was burned in excess of oxygen. The white solid from the combustion was dissolved in an excess of sodium hydroxide solution. The resulting salt with a solution of silver nitrate forms a bright yellow precipitate. Write down equations 38. Zinc was dissolved in an excess of very dilute nitric acid and an excess of alkali was added to the resulting solution to give a clear solution. Write down equations 39. The solution obtained by passing sulfur dioxide through bromine water was neutralized with barium hydroxide. The formed precipitate was separated, mixed with coke and calcined. When processing the calcined product with hydrochloric acid, a gas with the smell of rotten eggs is released. Write down equations 40. The substance formed by adding zinc powder to the ferric chloride solution was separated by filtration and dissolved in hot dilute nitric acid. The solution was evaporated, the solid residue was calcined, and the evolved gases were passed through a sodium hydroxide solution. Write down the equations 41. The gas evolved when a solution of hydrogen chloride with manganese (IV) oxide was heated was reacted with aluminum. The reaction product was dissolved in

6 water and added first an excess of sodium hydroxide solution, and then hydrochloric acid (excess). Write equations 42. A mixture of two colorless, colorless and odorless gases A and B was passed while heating over a catalyst containing iron, and the resulting gas C was neutralized with a solution of hydrobromic acid. The solution was evaporated and the residue was heated with caustic potash, resulting in the evolution of colorless gas B with a pungent odor. When gas B is burned in air, water and gas A are formed. Write down equations 43. Sulfur dioxide was passed through a solution of hydrogen peroxide. Water was evaporated from the resulting solution and magnesium turnings were added to the residue. The evolved gas was passed through a solution of copper sulfate. The precipitated black precipitate was separated and fired. Write the equations 44. A solution of hydrochloric acid was poured into the water-insoluble white salt, which occurs naturally in the form of a mineral widely used in construction and architecture, as a result, the salt dissolved and gas was released, when passed through lime water, a white precipitate formed; the precipitate dissolved upon further gas passage. When the resulting solution is boiled, a precipitate forms. Write the equations 45. When some mineral A, consisting of two elements, is fired, a gas is formed that has a pungent odor and decolorizes bromine water with the formation of two strong acids in solution. When substance B, consisting of the same elements as mineral A, but in a different ratio, interacts with concentrated hydrochloric acid, a gas with the smell of "rotten eggs" is released. When the released gases interact with each other, a simple yellow substance and water are formed. Write the equations 46. The substance released at the cathode during the electrolysis of sodium chloride melt was burned in oxygen. The resulting product was placed in a gas meter filled with carbon dioxide. The resulting substance was added to the ammonium chloride solution and the solution was heated. Write down equations 47. The nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was ignited. The resulting substance was introduced into a solution of potassium permanganate acidified with sulfuric acid, and the solution became discolored. The nitrogen-containing reaction product was placed in a sodium hydroxide solution and zinc dust was added, while a gas with a pungent characteristic odor was released. Write equations

7 48. When a solution of salt A interacts with alkali, a gelatinous, water-insoluble, blue substance was obtained, which was dissolved in colorless liquid B to form a blue solution. The solid product remaining after careful evaporation of the solution was calcined; at the same time, two gases were released, one of which is brown, and the second is part of the atmospheric air, and a black solid remains, which dissolves in liquid B with the formation of substance A. Write down equations 49. White phosphorus dissolves in a solution of caustic potassium with the release a garlic-smelling gas that ignites spontaneously in air. The solid product of the combustion reaction reacted with sodium hydroxide in such a ratio that the resulting white substance contains one hydrogen atom; when the latter is ignited, sodium pyrophosphate is formed. Write the equations 50. A solution of ferric chloride was treated with a solution of sodium hydroxide, the precipitate that formed was separated and heated. The solid reaction product was mixed with soda ash and calcined. Sodium nitrate and sodium hydroxide were added to the remaining substance and heated for a long time at a high temperature. Write the equations described 51. The gas released during the interaction of a solution of hydrogen chloride with potassium permanganate was passed through a solution of sodium tetrahydroxoaluminate. The formed precipitate was filtered off, calcined, and the solid residue was treated with hydrochloric acid. Write equations 52. The nitrogen-hydrogen mixture was heated to a temperature of 500 C and passed over iron under high pressure. The reaction products were passed through a nitric acid solution until it was neutralized. The resulting solution was carefully evaporated, the solid residue was calcined and the gas evolved during this process was passed over copper while heating, as a result a black solid was formed. Write equations 53. Trivalent chromium hydroxide was treated with hydrochloric acid. Potash was added to the resulting solution, the separated precipitate was separated and introduced into a concentrated solution of potassium hydroxide, as a result the precipitate was dissolved. After adding an excess of hydrochloric acid, a green solution was obtained. Write down equations 54. The substance obtained at the anode during the electrolysis of a sodium iodide solution with inert electrodes was reacted with potassium. The reaction product was heated with concentrated sulfuric acid and the evolved gas was passed through a hot potassium chromate solution. Write equations 55. Ferrous oxide was heated with dilute nitric acid. The solution was carefully evaporated, the solid residue was dissolved in water, into the resulting solution

8 iron powder was added and after a while filtered. A solution of potassium hydroxide was added to the filtrate, the precipitate that formed was separated and left in air, while the color of the substance changed. Write equations 56. One of the substances formed by the fusion of silicon oxide with magnesium dissolves in alkali. The evolved gas was reacted with sulfur, and the product of their interaction was treated with chlorine. Write the equations 57. The solid substance formed by the interaction of sulfur dioxide and hydrogen sulfide, when heated, interacts with aluminum. The reaction product was dissolved in dilute sulfuric acid, and potash was added to the resulting solution. Write equations 58. Unknown metal burned in oxygen. The reaction product, interacting with carbon dioxide, forms two substances: a solid, which reacts with a hydrochloric acid solution with the release of carbon dioxide, and a gaseous simple substance that supports combustion. Write equations 59. The product of the interaction of nitrogen and lithium was treated with water. The gas evolved as a result of the reaction was mixed with an excess of oxygen and, when heated, passed over a platinum catalyst; the resulting gas mixture had a brown color. Write equations 60. Copper shavings were dissolved in dilute nitric acid and the solution was neutralized with caustic potassium. The liberated blue substance was separated, calcined (the color of the substance changed to black), mixed with coke and re-calcined. Write equations 61. Phosphorus was burned in excess of chlorine, the resulting solid was mixed with phosphorus and heated. The reaction product was treated with a small amount of water, while a colorless gas with a pungent odor was evolved. The solution was added to a solution of potassium permanganate acidified with sulfuric acid, which became colorless as a result of the reaction. Write equations 62. Ferric chloride was treated with concentrated nitric acid while heating and the solution was carefully evaporated. The solid product was dissolved in water, potash was added to the resulting solution, and the precipitate formed was separated and calcined. Hydrogen gas was passed over the obtained substance while heating. Make the equations of four 63. An unknown salt, when interacting with a silver nitrate solution, forms a white precipitate and stains the burner flame yellow. When concentrated sulfuric acid interacts with this salt, a poisonous gas is formed, which is highly soluble in water. Iron dissolves in the resulting solution, and a very light colorless gas is released, which is used to obtain metals, such as copper, from their oxides. Write equations

9 64. Magnesium silicide was treated with a solution of hydrochloric acid and the evolved gas was burned. The solid reaction product was mixed with soda ash, the mixture was heated to melting and held for some time. After cooling, the reaction product (commonly known as “liquid glass”) was dissolved in water and treated with a sulfuric acid solution. Write down equations 65. A gas mixture of ammonia and a large excess of air was passed while heating over platinum, and after a while the reaction products were absorbed in a sodium hydroxide solution. After evaporation of the solution, a single product was obtained. Write down equations 66. Soda ash was added to the ferric chloride solution, and the precipitate formed was separated and calcined. Carbon monoxide was passed over the resulting substance while heating and the solid product of the last reaction was introduced into interaction with bromine. Write the equations 67. The product of the interaction of sulfur with aluminum (the reaction proceeds when heated) was dissolved in cold dilute hydrochloric acid and potassium carbonate was added to the solution. The formed precipitate was separated, mixed with sodium hydroxide and heated. Write down equations 68. Silicon (IV) chloride was heated in a mixture with hydrogen. The reaction product was mixed with magnesium powder, heated and treated with water; one of the resulting substances ignites spontaneously in air. Write down equations 69. A brown gas was passed through the excess potassium hydroxide solution in the presence of a large excess of air. Magnesium shavings were added to the resulting solution and heated; the released gas neutralized nitric acid. The resulting solution was carefully evaporated, and the solid reaction product was calcined. Write the equations described 70. Iron scale was dissolved in concentrated nitric acid while heating. The solution was carefully evaporated and the reaction product was dissolved in water. Iron powder was added to the resulting solution, after a while the solution was filtered and the filtrate was treated with a potassium hydroxide solution; as a result, a light green precipitate was formed, which quickly darkened in air. Write the equations 71. To a solution of soda ash was added a solution of aluminum chloride, the separated substance was separated and added to the sodium hydroxide solution. A solution of hydrochloric acid was added dropwise to the resulting solution until the formation of a precipitate ceased, which was separated and calcined. Write the equations described 72. Copper shavings were added to the solution of mercury (II) nitrate. After the end of the reaction, the solution was filtered and the filtrate was added dropwise to

10 to a solution containing sodium hydroxide and ammonium hydroxide. In this case, a short-term formation of a precipitate was observed, which dissolved with the formation of a bright blue solution. When an excess of sulfuric acid solution was added to the resulting solution, a color change occurred. Write the equations 73. The product of the interaction of magnesium phosphide with water was burned and the reaction products were absorbed in water. The resulting substance is used in industry to obtain double superphosphate from phosphorite. Write the equations described 74. The salt obtained by the interaction of zinc oxide with sulfuric acid was calcined at 800 C. The solid reaction product was treated with a concentrated alkali solution and carbon dioxide was passed through the resulting solution. Write the equations described 75. Iron powder was added to the ferric chloride solution and after a while the solution was filtered. Sodium hydroxide was added to the filtrate, the separated precipitate was separated and treated with hydrogen peroxide. An excess of potassium hydroxide and bromine solution was added to the resulting substance; as a result of the reaction, the color of bromine disappeared. Write down equations 76. Copper (I) oxide was treated with concentrated nitric acid, the solution was carefully evaporated and the solid residue was calcined. The gaseous reaction products were passed through water and magnesium shavings were added to the resulting solution, resulting in the release of a gas used in medicine. Write the equations described 77. Sulfur dioxide was passed through a solution of hydrogen peroxide. The solution was evaporated and copper shavings were added to the remaining liquid. The evolved gas was mixed with the gas that forms when iron (II) sulfide interacts with a solution of hydrobromic acid. Write down the equations 78. When diluted hydrochloric acid was added to the cooled solution of the yellow salt, which turns the flame into purple, the color changed to orange-red. After neutralizing the solution with concentrated alkali, the color of the solution returned to its original color. When barium chloride is added to the resulting solution, a yellow precipitate forms. The precipitate was filtered off and silver nitrate solution was added to the filtrate. Write the equations 79. Magnesium silicide was treated with a solution of hydrochloric acid, the reaction product was burned, the resulting solid was mixed with soda ash and heated to melt. After cooling the melt, it was treated with water and nitric acid was added to the resulting solution. Write the equations 80. The insoluble substance formed by adding sodium hydroxide to the ferric chloride solution was separated and dissolved in dilute sulfuric acid. V

11 the resulting solution was added zinc dust, the separated precipitate was filtered off and dissolved in concentrated hydrochloric acid. Write the equations described 81. Aluminum nitrate was calcined, the reaction product was mixed with soda ash and heated to melt. The resulting substance was dissolved in nitric acid and the resulting solution was neutralized with an ammonia solution, while the formation of a bulky gelatinous precipitate was observed. Write equations 82. Magnesium nitride was treated with excess water. When the evolved gas is passed both through bromine water or through a neutral solution of potassium permanganate, and when it is burned, the same gaseous product is formed. Write equations 83. Chlorine water smells like chlorine. When alkalizing, the smell disappears, and when added to the resulting solution of hydrochloric acid, it becomes stronger than it was before. Write the equations 84. The solid substance formed by heating malachite was heated in a hydrogen atmosphere. The reaction product was treated with concentrated sulfuric acid and, after separation from sulfuric acid, was introduced into a sodium chloride solution containing copper filings, as a result of which a precipitate was formed. Write equations 85. Phosphine was passed through a hot solution of concentrated nitric acid. The solution was neutralized with quicklime, the precipitate formed was separated, mixed with coke and silica and calcined. The reaction product, which glows in the dark, was heated in a concentrated sodium hydroxide solution. Write the equations described 86. The iron powder was dissolved in a large amount of dilute sulfuric acid, air was passed through the resulting solution and ammonium sulfide was added. The formed insoluble salt was separated and dissolved in a hot solution of concentrated nitric acid. Write down equations 87. Colorless gases are evolved when concentrated sulfuric acid is kept with both sodium chloride and sodium iodide. When these gases are passed through an aqueous ammonia solution, salts are formed. Write the equations described 88. Magnesium powder was mixed with silicon and heated. The reaction product was treated with cold water and the evolved gas was passed through hot water. The formed precipitate was separated, mixed with sodium hydroxide and heated to melting. Write the equations 89. One of the products of the interaction of ammonia with bromine, a gas that is part of the atmosphere, was mixed with hydrogen and heated in the presence of platinum. Formed

12, the gas mixture was passed through a hydrochloric acid solution and potassium nitrite was added to the resulting solution with slight heating. Write the equations described 90. The salt obtained by dissolving copper in dilute nitric acid was electrolyzed using graphite electrodes. The substance released at the anode was brought into interaction with sodium, and the resulting reaction product was placed in a vessel with carbon dioxide. Write the equations 91. Unknown substance A dissolves in concentrated hydrochloric acid, the dissolution process is accompanied by the release of gas with the smell of rotten eggs; after neutralization of the solution with alkali, a voluminous white (light green) precipitate is formed. When substance A is fired, two oxides are formed. One of them is a gas that has a characteristic pungent odor and decolorizes bromine water with the formation of two strong acids in solution. Write equations 92. Magnesium was heated in a vessel filled with gaseous ammonia. The resulting substance was dissolved in a concentrated solution of hydrobromic acid, the solution was evaporated and the residue was heated until the odor disappeared, after which an alkali solution was added. Write equations 93. Soda ash is added to the trivalent chromium sulfate solution. The separated precipitate was separated, transferred to a sodium hydroxide solution, bromine was added and heated. After neutralization of the reaction products with sulfuric acid, the solution acquires an orange color, which disappears when passing sulfur dioxide through the solution. Write equations 94. Quicklime was calcined with excess coke. The reaction product after treatment with water is used to absorb sulfur dioxide and carbon dioxide. Write the equations 95. The ferrous sulfide was treated with a solution of hydrochloric acid, the released gas was collected and burned in the air. The reaction products were passed through an excess of potassium hydroxide solution, after which a solution of potassium permanganate was added to the resulting solution. Write equations 96. The solid product of the thermal decomposition of malachite was dissolved by heating in concentrated nitric acid. The solution was carefully evaporated and the solid residue was calcined to give a black substance, which was heated in excess of ammonia (gas). Write equations 97. Red phosphorus was burned in a chlorine atmosphere. The reaction product was treated with a small amount of water and powdered

13 zinc. The evolved gas was passed over heated ferrous oxide. Write equations 98. A silvery-gray metal, which is attracted by a magnet, was added to hot concentrated sulfuric acid and heated. The solution was cooled and sodium hydroxide was added until the formation of an amorphous brown precipitate ceased. The precipitate was separated, calcined, and dissolved in concentrated hydrochloric acid while heating. Write equations 99. The magnesium shavings were heated in a nitrogen atmosphere and the reaction product was sequentially treated with boiling water, solutions of sulfuric acid and barium nitrate. Write down equations 100. Thermal decomposition of salt A in the presence of manganese dioxide resulted in the formation of a binary salt B and a gas that supports combustion and is part of the air; when this salt is heated without a catalyst, salt B and a salt of a higher oxygen-containing acid are formed. When salt A interacts with hydrochloric acid, a yellow-green poisonous gas (a simple substance) is released and salt B is formed. Salt B colors the flame purple; when it interacts with a solution of silver nitrate, a white precipitate forms. Write equations 101. The precipitate obtained by adding caustic soda to the aluminum sulfate solution was separated, calcined, mixed with soda ash and heated to melting. After treating the residue with sulfuric acid, the starting aluminum salt was obtained. Write the equations 102. The substance formed by the fusion of magnesium with silicon was treated with water, as a result a precipitate formed and a colorless gas was released. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate, with the formation of two water-insoluble binary substances. Write equations 103. The substance obtained by heating iron scale in a hydrogen atmosphere was introduced into hot concentrated sulfuric acid and heated. The resulting solution was evaporated, the residue was dissolved in water and treated with a solution of barium chloride. The solution was filtered and a copper plate was introduced into the filtrate, which after a while dissolved. Write the equations 104. Quicklime was "quenched" with water. A gas was passed into the resulting solution, which is released during the calcination of sodium bicarbonate, while the formation and subsequent dissolution of the precipitate was observed. Write the equations described 105. A mixture of nitrogen and hydrogen was passed sequentially over heated platinum and through a solution of sulfuric acid. Barium chloride was added to the solution and after separation

14 of the precipitated lime milk and heated. Write the equations described 106. Give examples of the interaction: o Two acids o Two bases o Two acid salts o Two acidic oxides Write equations 107. A solution of the average salt formed by passing sulfur dioxide through an alkali solution was left in air for a long time. The solid formed after the solution was evaporated was mixed with coke and heated to a high temperature. When hydrochloric acid is added to the solid product of the reaction, a gas with the smell of rotten eggs is released. Write equations 108. A solution of dilute sulfuric acid was added to the black powdery substance and heated. A solution of sodium hydroxide was poured into the resulting blue solution until the precipitation ceased. The precipitate was filtered off and heated. The reaction product was heated under a hydrogen atmosphere to give a red solid. Write equations 109. Red phosphorus was burned in an atmosphere of chlorine and a small amount (a few drops) of water was added to the reaction product. The evolved gas was dissolved in an excess of water, iron powder was added to the resulting solution, and the gaseous reaction product was passed over a heated copper plate oxidized to cupric oxide. Write equations 110. A solution of iron (III) chloride was subjected to electrolysis with graphite electrodes. The brown precipitate formed during electrolysis was filtered off and dissolved in a hot concentrated solution of sodium hydroxide, after which such an amount of sulfuric acid was added as needed to form a clear solution. The product released at the anode was passed through a hot potassium hydroxide solution. Write the equations 111. Aluminum chloride was added to the crystalline soda solution, the precipitate separated out was separated and treated with sodium hydroxide solution. The resulting solution was neutralized with nitric acid, the separated precipitate was separated and calcined. Write down equations 112. Ammonia was mixed with a large excess of air, heated in the presence of platinum, and after a while absorbed in water. Copper shavings added to the resulting

15 solution, dissolves with the evolution of brown gas. Write the equations described 113. When acid solution A is added to manganese dioxide, a poisonous gas of yellow-green color is released. Having passed the released gas through a hot solution of caustic potassium, a substance is obtained that is used in the manufacture of matches and some other incendiary compositions. During the thermal decomposition of the latter in the presence of manganese dioxide, a salt is formed, from which, when interacting with concentrated sulfuric acid, the original acid A can be obtained, and a colorless gas that is part of the atmospheric air. Write equations 114. The product of the interaction of silicon with chlorine is easily hydrolyzed. When a solid hydrolysis product fusion with both caustic and soda ash, the same substance remains. Write equations 115. To the solution obtained by dissolving iron in hot concentrated hydrochloric acid, sodium hydroxide was added. The separated precipitate was separated, left in air for a long time, and then dissolved in dilute hydrochloric acid. Write equations 116. When an orange substance is heated, it decomposes; Among the decomposition products are colorless gas and green solid. The released gas reacts with lithium even when heated slightly. The product of the last reaction interacts with water, while a gas with a pungent odor is released, which can reduce metals, such as copper, from their oxides. Write the equations described 117. A gas with the smell of rotten eggs was passed through concentrated sulfuric acid at room temperature. The formed precipitate was separated and treated with hot concentrated nitric acid; the evolved gas was dissolved in a large amount of water and a piece of copper was added to the resulting solution. Write equations 118. The salt obtained by dissolving iron in hot concentrated sulfuric acid was treated with an excess of sodium hydroxide solution. The resulting brown precipitate was filtered off and calcined. The resulting substance was fused with iron. Write equations 119. Metallic zinc was added to concentrated sulfuric acid. The resulting salt was isolated, dissolved in water, and barium nitrate was added to the solution. After separating the precipitate, magnesium chips were introduced into the solution, the solution was filtered, the filtrate was evaporated and calcined. Write equations 120. An unknown red substance was heated in chlorine and the reaction product was dissolved in water. An alkali was added to the resulting solution, the precipitated blue precipitate was filtered off and calcined. When heating the calcination product, which

16 is black; with coke, a red starting material was obtained. Write equations 121. Iodine was heated with excess phosphorus and the reaction product was treated with a small amount of water. The gaseous reaction product was completely neutralized with sodium hydroxide solution and silver nitrate was added to the resulting solution. Write equations 122. Iron was burned in chlorine. The reaction product was dissolved in water and iron filings were added to the solution. After a while, the solution was filtered and sodium sulfide was added to the filtrate. The separated precipitate was separated and treated with 20% sulfuric acid, obtaining an almost colorless solution. Write the equations 123. The gas released when heating solid sodium chloride with concentrated sulfuric acid was passed through a solution of potassium permanganate. The gaseous reaction product was taken up in a cold sodium hydroxide solution. After adding hydroiodic acid to the resulting solution, a pungent odor appears and the solution becomes dark in color. Write equations 124. Through the solution obtained by slaking lime, passed the gas, which is formed when getting quicklime from limestone; the result is a white precipitate. When acetic acid acts on the resulting precipitate, the same gas is released, which is formed when calcining calcium carbonate. Write equations 125. The red substance, which is used in the manufacture of matches, was burned in excess air and the reaction product was dissolved in a large amount of water when heated. After neutralizing the resulting solution with baking soda, silver nitrate was added to it. Write equations 126. Through a solution of sodium bromide passed the gas released during the interaction of hydrochloric acid with potassium permanganate. After the end of the reaction, the solution was evaporated, the residue was dissolved in water and subjected to electrolysis with graphite electrodes. The gaseous reaction products were mixed with each other and illuminated, resulting in an explosion. Write equations 127. The gas formed during the combustion of coke has been in contact with hot coal for a long time. The reaction product was subsequently passed through a layer of heated iron ore and quicklime. Write equations 128. Copper shavings were added to the heated concentrated sulfuric acid and the released gas was passed through a solution of sodium hydroxide (excess). The reaction product was isolated, dissolved in water and heated with sulfur, which, as a result of carrying out

17 reactions have dissolved. Dilute sulfuric acid was added to the resulting solution. Write equations 129. Hydrochloric acid was added to solutions of substance A and B, which color the flame yellow. When a solution of substance A interacts with hydrochloric acid, a colorless gas with an unpleasant odor is released, which forms a black precipitate when lead (II) nitrate is passed through the solution. When a solution of substance B with concentrated hydrochloric acid is heated, the color of the solution changes from yellow to green, and a poisonous gas of yellow-green color with a characteristic pungent odor is released. When barium nitrate is added to the solution of substance B, a yellow precipitate forms. Write down equations 130. A solution of hydrochloric acid was carefully added to the pyrolusite, and the evolved gas was passed into a beaker half filled with cold solution of caustic potash. After the end of the reaction, the glass was covered with a cardboard and left, while the glass was illuminated by the sun's rays; after a while, a smoldering splinter was brought into the glass, which flashed brightly. Write equations 131. The precipitate obtained by the interaction of a solution of an aluminum salt and an alkali was calcined. The reaction product was dissolved in a concentrated hot alkali solution. Carbon dioxide was passed through the resulting solution, resulting in the formation of a precipitate. Write the equations 132. The black powder, which was formed by prolonged heating of the red metal in excess of air, was dissolved in 10% sulfuric acid and a blue solution was obtained. Alkali was added to the solution, and the precipitate formed was separated and dissolved in an excess of concentrated ammonia solution. Write equations 133. Phosphorus was added to the solid matter, which is formed by burning phosphorus in excess of chlorine, and the mixture was heated. The reaction product was treated with a small amount of hot water and a solution of potassium permanganate acidified with sulfuric acid was added to the resulting solution. Write the equations 134. Carbon dioxide was passed through the barite water. Barium hydroxide was added to the resulting solution, the reaction product was separated and dissolved in phosphoric acid. Write equations 135. Zinc nitrate was calcined, the reaction product was treated with sodium hydroxide solution while heating. Carbon dioxide was passed through the resulting solution until the precipitation ceased, after which it was treated with an excess of concentrated ammonia, and the precipitate dissolved. Write the equations

18 136. Two vessels contain solutions of unknown substances. When barium chloride is added to the solution of the first substance, a white precipitate is formed, insoluble in water and acids. A white precipitate also falls out when the silver nitrate solution is added to the sample taken from the second vessel. When a sample of the first solution with sodium hydroxide is heated, a gas with a pungent odor is released. When the second solution interacts with sodium chromate, a yellow precipitate forms. Write equations 137. Sulfur dioxide was dissolved in water and the solution was neutralized by adding sodium hydroxide. Hydrogen peroxide was added to the resulting solution and after the end of the reaction, sulfuric acid. Write equations 138. Zinc was dissolved in very dilute nitric acid, the resulting solution was carefully evaporated and the residue was calcined. The residue was mixed with coke and heated. Write equations 139. Substances released at the cathode and anode during the electrolysis of sodium iodide solution with graphite electrodes, react with each other. The reaction product interacts with concentrated sulfuric acid with the release of gas, which was passed through a solution of potassium hydroxide. Write equations 140. The substance that is formed during the electrolysis of bauxite melt in cryolite dissolves both in a solution of hydrochloric acid and and in p solution of alkali with the release of the same gas. When the resulting solutions are mixed, a white bulk precipitate is formed. Write equations 141. Concentrated hydrochloric acid was added to lead (IV) oxide while heating. The evolved gas was passed through a heated potassium hydroxide solution. The solution was cooled, the oxygenate acid salt was filtered off and dried. When the resulting salt is heated with hydrochloric acid, a poisonous gas is released, and when it is heated in the presence of manganese dioxide, the gas that is part of the atmosphere. Write equations 142. The brown precipitate obtained by the interaction of sodium sulfite with an aqueous solution of potassium permanganate was filtered off and treated with concentrated sulfuric acid. The evolved gas when heated reacts with aluminum, and the resulting substance with a solution of hydrochloric acid. Write equations 143. Calcium was heated in a hydrogen atmosphere. The reaction product was treated with water, the evolved gas was passed over heated zinc oxide, and soda ash was added to the solution. Write equations 144. Silver nitrate was ignited and the solid reaction product was heated in oxygen at an increased pressure. The resulting substance dissolves in excess

19 concentrated ammonia. When passing through the resulting solution of hydrogen sulfide, a black precipitate is formed. Write equations 145. The solid, which is formed by heating phosphorus and phosphorus pentachloride, was dissolved in a large amount of water. Part of the resulting solution was added to a solution of potassium permanganate acidified with sulfuric acid, the latter discolored. Write equations 146. Several zinc granules were introduced into a vessel with concentrated sulfuric acid. The evolved gas was passed through a solution of lead (II) acetate, the precipitate was separated, subjected to roasting, and the resulting gas was brought into interaction with an aqueous solution of potassium permanganate. Write equations 147. Several zinc granules were dissolved by heating in a sodium hydroxide solution. Nitric acid was added to the resulting solution in small portions until a precipitate was formed. The precipitate was separated, dissolved in dilute nitric acid, the solution was carefully evaporated, and the residue was calcined. Write equations 148. The gas released when copper is dissolved in hot concentrated nitric acid can interact with both the gas released during the treatment of copper with hot concentrated sulfuric acid and with copper. Write equations 149. A solution of iron (III) chloride was subjected to electrolysis with graphite electrodes. The separated brown precipitate (a by-product of electrolysis) was filtered off, calcined, and fused with the substance formed at the cathode. Another substance, also released at the cathode, was introduced into a reaction with the product released during electrolysis at the anode; the reaction proceeds under illumination and with an explosion. Write equations 150. The water-insoluble white salt, which occurs in nature in the form of a mineral widely used in construction and architecture, was calcined to 1000 C. After cooling, water was added to the solid residue and a gaseous decomposition reaction product was passed through the resulting solution. As a result, a white precipitate, which dissolved upon further gas passage. Write the equations

The correct solution to task 31 must contain the equations of four. For the correct record of each reaction equation, you can get 1 point. You can get a maximum of 4 points for completing this task. Every faithful

Reactions confirming the relationship of various classes of inorganic substances. 1. Sodium was fused with sulfur. The resulting compound was treated with hydrochloric acid, the released gas completely reacted with

2016 1. 4.2 g of lithium was dissolved in 250 ml of water, then 200 g of a 20% solution of copper (ii) sulfate was added. Determine the mass fraction of salt in the resulting answer.In the answer, write down the reaction equations that are indicated in

Elements IА and IIА of subgroups 1. 8. 9. 2. 10. 11. 3. 4. 12. 5. 13. 14. 6. 7. 15. 16. 1 17. 26. 18. 27. 19. 28. 20. 21. 29. 22. 23. 30. 24. 31. 25. 32. 2 33. 39. The interaction of calcium oxide with water refers to

Iron 1. 7. Are the following judgments about the properties of iron and aluminum oxides correct? A. Both aluminum and iron form stable oxides in the +3 oxidation state. B. Iron (III) oxide is amphoteric. 2.

Collection of problems in chemistry for the 9th medical class compiled by I.A. Moscow Education Center 109 2012 Mass fraction of a dissolved substance. 1. 250 g of solution contains 50 g of sodium chloride. Define

Chemistry Olympiad "The Future of the Arctic" 2016-17 academic year Full-time round Grade 9 (50 points) Task 1. Elements A and B are in the same group, but in different periods, elements C and D are in the same period,

A11 Chemistry Tasks 1. Iron (ii) sulfide reacts with a solution of each of two substances: Iron (II) sulfide is an insoluble salt, so it will not react with other salts, but will react

Reactions confirming the relationship between different classes of inorganic substances (analysis of tasks 37). Chemistry teacher MBOU SOSH 25 Kornilova Tatyana Pavlovna. Sign of the reaction accompanying chemical transformations

1. Interrelation of different classes of inorganic substances When solving problems of this type, we especially note: 1. Most of the reactions in the proposed chain of transformations are redox reactions. So

Tasks C2 in chemistry 1. Substances are given: phosphorus, chlorine, aqueous solutions of sulfuric acid and potassium hydroxide. 1. 2. 3. 4. 2. Given: hydrobromic acid, sodium permanganate, sodium hydroxide and bromine. Recorded

Features of preparation for the exam 2017, in chemistry. Drawing up the reaction equations confirming the relationship of various classes of inorganic substances "Thought experiment" (Task 31) Expert GIA Bubnova

4. Tasks for finding the mass (volume, amount of substance), mass (volume) fraction of the reaction product and mass fraction (mass) of a chemical compound in the mixture. The solution to the problem should begin with an analysis

1. From the proposed list of substances, select two substances with each of which iron reacts without heating. zinc chloride copper (ii) sulfate concentrated nitric acid dilute hydrochloric acid

1 .. Amphoteric oxides are: A) strontium oxide D) beryllium oxide B) iron (II) oxide E) lead (IV) oxide C) iron oxide (iii) E) silicon oxide (iv) IOP 2. In the list of substances to hydroxides include:

Collection of problems for the 11th medical class compiled by I.A. Moscow Education Center 109 2012 BASIC REGULATIONS OF CHEMICAL REACTIONS 1. When boron is burned, 13.92 g of oxide was obtained

Computational problems in inorganic chemistry 1. Mass fraction of metal in oxide of composition characterizing metal: equal to 71.4%. Select statements a) NOT reduced by hydrogen from oxide b) used

Reaction rate, its dependence on various factors 1. To increase the reaction rate, it is necessary to increase the pressure add carbon monoxide (1v) cool the system remove carbon monoxide (1v) 2. Speed

Test tasks on the topic "Halogens and their compounds" 1. 8. Are the following judgments about the properties of chlorine correct? 2. The number of fully filled energy sublevels for a Cl particle is: 1) 2 2) 3 3) 4 4)

OPTION 1 10 class 1. Guided by the Periodic Table, indicate the symbol of the chemical element, the ion of which the electronic formula corresponds: E 3+ = 1s 2 2s 2 2p 6 3s 2 3p 6 3d 5. 2. A mixture of carbon oxides

Task 1. School tour of the All-Russian Olympiad in Chemistry 2015-2016 academic year Problems for grades 5-8 (120 minutes) Maximum number of 50 points Three elements A, B, C are in one period of the table

MINISTRY OF HEALTH OF THE RUSSIAN FEDERATION GENERAL PHARMACOPEY ARTICLE General reactions to the authenticity of the OFS.1.2.2.0001.15 Instead of Art. GF XI, issue 1 Aluminum. About 15 mg of the drug is dissolved

Solution of computational problems 1. When draining 160 g of a solution of barium nitrate with a mass fraction of 10% and 50 g of a solution of potassium chromate with a mass fraction of 11%, a precipitate formed. Calculate the mass fraction of potassium nitrate in the formed

Mid-term control in the discipline "Analytical chemistry and laboratory research technique" for students of the specialty "Preventive medicine" Section. Qualitative analysis 1. What is the reaction to an ion

ALL-RUSSIAN CHEMISTRY OLYMPIAD. 2017 2018 account THE MUNICIPAL STAGE. 9 CLASS Tasks, answers, assessment criteria General instructions: if the task requires calculations, they must be

INTELLIGENT MARATHON 10 CLASS 1 round 1. In an aqueous solution of barium iodide, the mass fraction of electrons is 2.852 * 10-4. Determine the mass fraction of salt in the solution. 2 points 2. There is a mixture of oxygen and ozone,

1. A precipitate is not formed during the interaction of aqueous solutions and and and 2. The precipitate is not formed during the interaction of aqueous solutions and and and 3. Water is formed in the reaction of ion exchange during the interaction of and and and

79 1. TOPIC: BERYLLIUM, MAGNESIUM AND THEIR COMPOUNDS Experiment 1. Beryllium hydroxide and its properties Into two test tubes add 3-4 drops of beryllium salt solution. Add an alkali solution to each tube until

Municipal autonomous educational institution basic general education school of the village of Zarubino Tickets for chemistry Chemistry teacher Somova N.Kh. 2012 Exam tickets in chemistry Theoretical

6 Ninth grade Problem 9-1 Below is the scheme of transformations of compounds X 1 X 5 of element X. X 1 black 1200 o C X 2 red HCl pp X 3 blue-green crystals gas Y Na 2 CO 3 to X 4 white + CaCO 3 + H 2

4.1.2 Tasks of grade 10 1. One of the important characteristics of a covalent bond is its length. For which of the listed connections is the maximum link length? 1. HF 3. HBr 2. HCl 4. HI 2. Most inorganic

Bank of tasks 11 grade chemistry 1. The electronic configuration corresponds to the ion: 2. The particles and and and and and have the same configuration 3. The atoms of magnesium and

Chemical properties of bases and acids 1. Reacts with potassium hydroxide solution 2. Sulfuric acid solution reacts with solution 3. Sulfuric acid solution does not react 4. Copper (ii) hydroxide reacts

Theoretical round Grade 9 Grade 9 Problem 1. A solution containing 5.55 g of calcium hydroxide absorbed 3.96 g of carbon dioxide. What is the amount of sediment formed in this case? Ca (OH) 2 + CO 2 = CaCO 3 + H 2 O (1)

Tasks A8 in chemistry 1. Zinc interacts with a solution Metals react with solutions of salts of less active metals. Mg, Na, Ca are more active metals than zinc, so the reaction with these salts is not possible.

Non-standard tasks in chemistry: from simple to complex V.V. Eremin Faculty of Chemistry, Moscow State University University Saturdays. 03 October 2015 1 Unusual mass fraction Determine the hydrocarbon formula in which

Grade 8 Explanatory note This work program is based on the Model Program of Secondary (Complete) General Education in Chemistry (basic level) for Grades 8 9, recommended by letter

4.1.3 Tasks of grade 11 1. One of the important characteristics of a covalent bond is its length. For which of the following connections is the minimum link length? 1. HF 2. HCl 3. HBr 4. HI 2. Large quantities

TASK 1 1) To a mixture of sodium carbonate and potassium bicarbonate with a total mass of 24.0 g, in which the mass of carbon atoms is 24 times the mass of hydrogen atoms, an excess of 10% sulfuric acid was added. Define

18 Laboratory work 2 ELEMENTAL ANALYSIS OF ORGANIC COMPOUNDS PURPOSE OF THE WORK: to determine the qualitative composition of organic matter. Reagents and materials: unknown organic matter; copper oxide

EXAMINATION TICKETS OF THE STATE FINAL CERTIFICATION IN CHEMISTRY FOR BASIC GENERAL EDUCATION PROGRAMS in 2018 TICKET 1 1. Periodic law and periodic system of chemical elements D.I.

1 2 3 Tasks С 2. Substances are given. Write the equations for four possible reactions between these substances. 4 5 6 7 8 9 10 11 12 13 54. Copper nitrate was calcined. The resulting solid was dissolved in dilute

Tickets for the transfer exam in chemistry in grade 8 Ticket 1 1. Subject of chemistry. Substances. Substances are simple and complex. Properties of substances. 2. Acids. Their classification and properties. Ticket 2 1. Transformations of substances.

1. Which equation corresponds to the decomposition reaction? 2. Which equation corresponds to the exchange reaction? 3. Which equation corresponds to the substitution reaction? 4. In a decomposition reaction accompanied by a change

Full-time stage. Grade 11. Solutions. Task 1. A mixture of three gases A, B, C has a hydrogen density of 14. A 168 g portion of this mixture was passed through an excess of bromine solution in an inert solvent

46 Laboratory work 9 CARBONIC ACIDS AND THEIR FUNCTIONAL DERIVATIVES PURPOSE OF THE WORK: to study some physical and chemical properties of mono- and polybasic carboxylic acids and their functional derivatives:

CHEMISTRY, Grade 11 Option 1, March 2014 Regional diagnostic work on CHEMISTRY OPTION 1 Part A When performing tasks A1 A9 in the answer form 1, under the number of the task being performed, put an "x" in the box,

CHEMISTRY, grade 11 Option 1, March 2014 Regional diagnostic work on CHEMISTRY OPTION 1 Part A When performing tasks A1 A9 in the answer form 1, under the number of the task being performed, put an "x" in the box,

Tasks C4 in chemistry 1. To a solution of sodium hydroxide weighing 1200 g was added 490 g of a 40% sulfuric acid solution. To neutralize the resulting solution, it took 143 g of crystalline soda Na

Tasks A20 in chemistry 1. The rate of reaction of nitrogen with hydrogen will decrease with 1) a decrease in temperature 2) an increase in nitrogen concentration 3) use of a catalyst 4) an increase in pressure Factors influencing

Terms of assignments for the qualifying stage (online round) of the Open Chemistry Olympiad 2016/2017 academic year Qualifying stage. Online tour. Grade 9. Conditions. Task 1.1. The mass of an atom of element X is 1.66 10-24

Option 2 1. Give the formulas of two chromium compounds in which this element has different oxidation states. Write down the reactions for obtaining each of the compounds you give. Solution. For instance,

Tasks B5 in chemistry 1. Establish a correspondence between the name of the oxide and the formulas of substances with which it can interact. OXIDE NAME A) potassium oxide carbon monoxide (ii) B) chromium oxide (iii) oxide

9 class 1. During the dissociation of 1 mole of what substances are formed the largest amount (in moles) of ions? 1. Sodium sulfate 2. Iron (III) chloride 3. Sodium phosphate 4. Cobalt (II) nitrate 2. Indicate the compounds

Chemical reaction. Conditions and signs of chemical reactions. Chemical Equations 1. Which equation corresponds to the decomposition reaction? 2. Which equation corresponds to the exchange reaction? 3. What

2014 ALL-RUSSIAN OLYMPIAD FOR SCHOOLS IN CHEMISTRY MUNICIPAL STAGE 9 CLASS Task 1. Complete the tasks, choosing one correct answer from the proposed ones. Enter the answers in the table. 1. Relative density

IA Gromchenko Collection of tasks in chemistry for grade 8 Moscow Education Center 109 2009 1. Mass fraction of an element. Calculations by formulas. 1.1. Which substance has a heavier molecule: BaO, P 2 O 5, Fe 2 O 3? 1.2.

7. LABORATORY WORKS The main goal of laboratory work in chemistry is to acquire the skills to independently perform a chemical experiment, the ability to generalize and analyze the results obtained,

Chemistry. Answer keys Grade 10 Task 1. During excavations in the Crimea, an archaeological expedition found two unusual coins of an unknown era from an unknown alloy. To analyze the composition of the coins, they were given to

Chemistry - grades 8-9. The maximum number of points is 100. 9-1. The same amount of metal reacts with 0.8 g of oxygen and 8.0 g of halogen. Identify the halogen in question. Confirm answer

Task 32 on the Unified State Exam in Chemistry-2018 (the former task C2 of the "new type") contains a description of an experiment consisting of sequentially conducted chemical reactions and laboratory methods for separating reaction products ( thought experiment).

According to my observations, this task is difficult for many students. This is largely due to the increasingly academic nature of teaching chemistry in schools and courses, when not enough attention is paid to the study of the features of work in the laboratory and the actual conduct of laboratory experiments.

Therefore, I decided to systematize and summarize the material on the so-called. "Laboratory" chemistry. This article examines examples of assignment 32 in the exam in chemistry-2018 (the former assignment C2), with a detailed analysis and analysis of the solution.

This assignment requires a good understanding of some topics of general chemistry and element chemistry, namely: the main , chemical properties and production, acids, and salts, and the relationship between different classes of inorganic substances; properties of simple substances - metals and non-metals; ; ; , , halogens.

1. The solution obtained by reacting copper with concentrated nitric acid was evaporated and the precipitate was calcined. The gaseous products of the decomposition reaction are completely absorbed in water, and hydrogen was passed over the solid residue. Write down the equations for the reactions described.

Analysis and solution.

"Keywords" - concentrated nitric acid and copper.

Copper is an inactive metal and exhibits the properties of a reducing agent.

Keywords: " … The resulting product was sequentially treated with sulfur dioxide and barium hydroxide solution". Sodium sulfate obtained in the previous step enters into an ion exchange reaction with barium hydroxide to precipitate barium sulfate (equation 4).

1) 2NaCl = 2Na + Cl 2

2) 2Na + O 2 = Na 2 O 2

3) Na 2 O 2 + SO 2 = Na 2 SO 4

4) Na 2 SO 4 + Ba (OH) 2 = NaOH + BaSO 4

5.The decomposition products of ammonium chloride were sequentially passed through a heated tube containing copper (II) oxide and then through a bottle with phosphorus (V) oxide. Write down the equations for the reactions described.

Analysis and solution.

Keywords: " Decomposition products of ammonium chloride... ". Ammonium chloride is a salt that decomposes when solid salt is heated into gaseous ammonia and hydrogen chloride gas (equation 1)

Further, the products of reactions 2 and 3 are passed through a container with phosphorus (V) oxide. We analyze the possibility of a chemical reaction between substances. The simple substance copper is chemically inactive and does not react with phosphorus. The simple substance nitrogen is also chemically inactive; it does not react with phosphorus (V) oxide. But with acidic oxide of phosphorus (V), water vapor reacts perfectly with the formation of orthophosphoric acid (equation 4).

1) NH 4 Cl = NH 3 + HCl

2) CuO + 2HCl = CuCl 2 + H2O

3) 3CuO + 2NH 3 = 3Cu + N 2 + 3H2O

4) 3H 2 O + P 2 O 5 = 2H 3 PO 4

6. A solution of hydrochloric acid was poured into the water-insoluble white salt, which occurs in nature in the form of a mineral widely used in construction and architecture, as a result, the salt dissolved and gas was released, when passed through lime water, a white precipitate formed; the precipitate dissolved upon further gas passage. When the resulting solution is boiled, a precipitate forms. Write down the equations for the reactions described.

Analysis and solution.

It is well known from the school chemistry course that the water-insoluble white salt, which occurs in nature in the form of a mineral widely used in construction and architecture, is calcium carbonate CaCO 3. Insoluble salts dissolve under the action of stronger acids, in this case, hydrochloric acid (equation 1).

Generated gas passed through lime water Ca (OH) 2. Carbon dioxide is a typical acidic oxide that, when reacted with alkali, forms a salt called calcium carbonate (equation 2). Further the precipitate dissolved upon further gas passage. A very important property is discussed here: medium salts of polybasic acids under the action of an excess of acid form more acidic salts ... Calcium carbonate in excess of carbon dioxide forms a more acidic salt - calcium bicarbonate Ca (HCO 3) 2, which is highly soluble in water (equation 3).

The properties of acidic salts are largely composed of the properties of the compounds that form acidic salts.. The properties of calcium bicarbonate are determined by the properties of the compounds forming it - carbonic acid H 2 CO 3 and calcium carbonate. It is easy to deduce that when boiled, bicarbonate will decompose into calcium carbonate (it is distributed at higher temperatures, about 1200 degrees Celsius), carbon dioxide and water (equation 4).

1) CaCO 3 + 2HCl = CaCl 2 + CO 2 + H 2 O

2) CO 2 + Ca (OH) 2 = CaCO 3 + H 2 O

3) CaCO 3 + H 2 O + CO 2 = Ca (HCO 3) 2

4) Ca (HCO 3) 2 = CaCO 3 + H 2 O + CO 2

7. Substance obtained at anode during the electrolysis of sodium iodide solution with inert electrodes, reacted with hydrogen sulfide. The resulting solid was fused with aluminum and the product was dissolved in water. Write down the equations for the reactions described.

Analysis and solution.

The electrolysis of a sodium iodide solution with inert electrodes is described by the equation:

1.2NaI + 2H 2 O = 2NaOH + H 2 + I 2

2.I 2 0 + H 2 S -2 = 2HI - + S 0

This resulted in the formation of solid sulfur. Sulfur reacts with aluminum when alloyed to form aluminum sulfide. Most non-metals react with metals to form binary compounds:

3.3S 0 + 2Al 0 = Al 2 +3 S 3 -2

The product of the reaction of aluminum with sulfur - aluminum sulfide - when dissolved in water, irreversibly decomposes into aluminum hydroxide and hydrogen sulfide:

4.Al 2 S 3 + 12H 2 O = 2Al (OH) 3 + 3H 2 S

Such reactions are also referred to as reactions. Cases of irreversible hydrolysis are discussed in detail in.

8. The gas released during the interaction of hydrogen chloride with potassium permanganate reacts with iron. The reaction product was dissolved in water, and sodium sulfide was added thereto. The lighter of the formed insoluble substances was separated and reacted with hot concentrated nitric acid. Write down the equations for the reactions described.

9. Chromium (III) sulfide was treated with water, while gas evolved and an insoluble substance remained. A sodium hydroxide solution was added to this substance and chlorine gas was passed through, while the solution acquired a yellow color. The solution was acidified with sulfuric acid; as a result, the color changed to orange; gas evolved during the treatment of sulfide with water was passed through the resulting solution, and the color of the solution changed to green. Write down the equations for the reactions described.

Analysis and solution.

Keywords: " Chromium (III) sulfide was treated with water, while gas evolved and an insoluble substance remained«. Chromium (III) sulfide decomposes under the action of water into hydroxide and hydrogen sulfide ... The hydrolysis reactions of such compounds are discussed in detail in. (reaction 1)

1) Cr 2 S 3 + 6H 2 O = 2Cr (OH) 3 + 3H 2 S

Key words: "... added a solution of caustic soda and let in gaseous chlorine, while the solution acquired a yellow color." Under the influence of chlorine in an alkaline environment, chromium +3 is oxidized to chromium +6 ... Chromium +6 forms acid oxide and hydroxide, in a solution of sodium hydroxide forms a stable yellow salt - sodium chromate (reaction 2).

2) 2Cr +3 (OH) 3 + 3Cl 0 2 + 10NaOH = 2Na 2 Cr +6 O 4 + 6NaCl - + 8H 2 O

Further, the keywords: “ The solution was acidified with sulfuric acid, as a result, the color changed to orange«. Salt-chromates in an acidic medium pass into dichromates. Yellow sodium chromate in an acidic medium turns into orange sodium dichromate (reaction 3). This is not an OVR!

3) 2Na 2 CrO 4 + H 2 SO 4 = Na 2 Cr 2 O 7 + Na 2 SO 4 + H 2 O.

Further: "... through the resulting solution passed the gas released during the treatment of sulfide with water, and the color of the solution changed to green". Sodium dichromate is a strong oxidizing agent; when interacting with hydrogen sulfide, it is reduced to a trivalent chromium salt. Chromium (III) compounds are amphoteric and form salts in an acidic medium. Chromium (III) salts color the solution green (reaction 4).

4) Na 2 Cr +6 2 O 7 + 3H 2 S -2 + 4H 2 SO 4 = 3S 0 + Cr +3 2 (SO 4) 3 + Na 2 SO 4 + 7H 2 O

10. Obtaining a black-and-white image when photographing is based on the decomposition of a salt of an unknown metal under the action of light. When this metal is dissolved in dilute nitric acid, a colorless gas is released, which in air quickly changes its color to brown, and a salt is formed that interacts with sodium bromide to form a yellowish curdled precipitate. The anion in the salt used in photography is the anion of an acid that forms simultaneously with sulfuric acid, when bromine water and sulfur dioxide react. Write down the equations for the reactions described.

11. Sodium hydroxide solution was added dropwise to the solution obtained by the interaction of aluminum with dilute sulfuric acid until a precipitate was formed. The formed white precipitate was filtered off and calcined. The resulting material was fused with sodium carbonate. Write down the equations for the reactions described.

Analysis and solution.

Diluted sulfuric acid, when interacting with metals, behaves like ordinary mineral acid. Metals located in the series of electrochemical activity to the left of hydrogen, when interacting with mineral acids, displace hydrogen:

1.2Al 0 + 3H + 2 SO 4 = Al +3 2 (SO 4) 3 + 3H 0 2

Further, aluminum sulfate reacts with sodium hydroxide. The condition states that sodium hydroxide was added dropwise. This means that sodium hydroxide was in short supply, and aluminum sulfate was in significant excess. Under these conditions, a precipitate of aluminum hydroxide is formed:

2. Al 2 (SO 4) 3 + 6NaOH = 2Al (OH) 3 + 3Na 2 SO 4

The white precipitate is aluminum hydroxide, insoluble in water. P When ignited, insoluble hydroxides decompose into water and the corresponding oxide :

3. 2Al (OH) 3 = Al 2 O 3 + 3H 2 O

The resulting substance - aluminum oxide - was fused with sodium carbonate. In the melt, less volatile oxides displace more volatile ones from salts. Carbonate is a salt that corresponds to a volatile oxide, carbon dioxide. Accordingly, when alkali metal carbonates are fused with solid oxides (acidic and amphoteric), a salt corresponding to this oxide and carbon dioxide are formed:

4. Al 2 O 3 + Na 2 CO 3 = 2NaAlO 2 + CO 2

12. A constant electric current was passed through a solution of copper (II) chloride using graphite electrodes. The electrolysis product released at the cathode was dissolved in concentrated nitric acid. The resulting gas was collected and passed through a sodium hydroxide solution. The gaseous electrolysis product released at the anode was passed through a hot sodium hydroxide solution. Write down the equations for the reactions described.

13. A simple substance obtained by heating a mixture of calcium phosphate with coke and silicon oxide is dissolved in a solution of caustic potassium. The evolved gaseous substance was burned, the combustion products were collected and cooled, and silver nitrate was added to the resulting solution. Write down the equations for the reactions described.

14. The offensive liquid formed by the interaction of hydrogen bromide with potassium permanganate was separated and heated with iron shavings. The reaction product was dissolved in water, and a cesium hydroxide solution was added thereto. The formed precipitate was filtered off and calcined. Write down the equations for the reactions described.

15. Electric discharges were passed over the surface of the caustic soda solution, while the air turned brown, and the color disappeared after a while. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. Keeping a mixture of salts in air leads to the formation of one substance. Write down the equations for the reactions described.

Calcium was dissolved in water. When passing through the resulting solution of sulfur dioxide, a white precipitate is formed, which dissolves when passing an excess of gas. Adding alkali to the resulting solution leads to the formation of a white precipitate. Write down the equations for the reactions described.

When a simple yellow substance is burned in air, a gas with a pungent odor is formed. This gas is also released when some iron-containing mineral is burned in air. When diluted sulfuric acid acts on a substance consisting of the same elements as the mineral, but in a different ratio, a gas is released with a characteristic smell of rotten eggs. When the released gases interact with each other, an initial simple substance is formed. Write down the equations for the reactions described.

The gaseous product of the interaction of dry sodium chloride with concentrated sulfuric acid was reacted with a solution of potassium permanganate. The evolved gas was passed through a sodium sulfide solution. The precipitated yellow precipitate is dissolved in a concentrated solution of sodium hydroxide. Write down the equations for the reactions described.

The gas formed by passing hydrogen chloride through a hot potassium chromate solution interacts with iron. The reaction product was dissolved in water, and sodium sulfide was added thereto. The lighter of the formed insoluble substances was separated and reacted with concentrated sulfuric acid while heating. Write down the equations for the reactions described.

The two salts contain the same cation. The thermal decay of the first of them resembles a volcanic eruption, with the release of an inactive colorless gas that is part of the atmosphere. When the second salt interacts with a solution of silver nitrate, a white cheesy precipitate is formed, and when it is heated with an alkali solution, a colorless poisonous gas with a pungent odor is released; this gas can also be obtained by the interaction of magnesium nitride with water. Write down the equations for the reactions described.

An excess of sodium hydroxide solution was added to the aluminum sulfate solution. Hydrochloric acid was added to the resulting solution in small portions, while the formation of a bulk white precipitate was observed, which dissolved upon further addition of acid. Sodium carbonate solution was poured into the resulting solution. Write down the equations for the reactions described.

Electric discharges were passed over the surface of the caustic soda solution poured into the flask, while the air in the flask turned brown, which disappeared after some time. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. When this mixture is heated, gas is released and only one substance remains. Write down the equations for the reactions described.

Zinc oxide was dissolved in a solution of hydrochloric acid and the solution was neutralized by adding sodium hydroxide. The separated white gelatinous substance was separated and treated with an excess of alkali solution, while the precipitate was completely dissolved. Neutralization of the resulting solution with an acid, for example, nitric acid, leads to the re-formation of a gelatinous precipitate. Write down the equations for the reactions described.

The substance obtained at the cathode during the electrolysis of molten copper (II) chloride reacts with sulfur. The resulting product was treated with concentrated nitric acid and the evolved gas was passed through a barium hydroxide solution. Write down the equations for the reactions described.

A mixture of calcium orthophosphate, coke and sand was heated in an electric furnace. One of the products of this reaction can spontaneously ignite in air. The solid combustion product of this substance was dissolved in water when heated, and gaseous ammonia was passed through the resulting solution. Write down the equations for the reactions described.

The substance obtained at the cathode during the electrolysis of a solution of iron (II) chloride was fused with sulfur and the product of this reaction was fired. The resulting gas was passed through a barium hydroxide solution. Write down the equations for the reactions described.

Copper wire was introduced into the heated concentrated sulfuric acid and the evolved gas was passed through an excess of sodium hydroxide solution. The solution was carefully evaporated, the solid residue was dissolved in water and heated with powdered sulfur. Unreacted sulfur was separated by filtration and sulfuric acid was added to the solution, while the formation of a precipitate and the evolution of gas with a pungent odor were observed. Write down the equations for the reactions described.

After a short heating of an unknown powdery orange substance, a spontaneous reaction begins, which is accompanied by a change in color to green, the release of gas and sparks. The solid residue was mixed with caustic potassium and heated, the resulting substance was introduced into a dilute solution of hydrochloric acid, and a green precipitate was formed, which dissolves in an excess of acid. Write down the equations for the reactions described.

The two salts turn the flame purple. One of them is colorless, and when it is slightly heated with concentrated sulfuric acid, the liquid is distilled off, in which copper dissolves; the last transformation is accompanied by the evolution of brown gas. When the second salt of the sulfuric acid solution is added to the solution, the yellow color of the solution changes to orange, and when the resulting solution is neutralized with alkali, the original color is restored. Write down the equations for the reactions described.

The iron (III) chloride solution was electrolyzed with graphite electrodes. The brown precipitate formed as a by-product of electrolysis was filtered off and calcined. The substance formed at the cathode was dissolved in concentrated nitric acid with heating. The product released at the anode was passed through a cold potassium hydroxide solution. Write down the equations for the reactions described.

The gas released during the interaction of hydrogen chloride with berthollet's salt was reacted with aluminum. The reaction product was dissolved in water and sodium hydroxide was added until the precipitation ceased, which was separated and calcined. Write down the equations for the reactions described.

The unknown salt is colorless and turns the flame yellow. When this salt is slightly heated with concentrated sulfuric acid, the liquid is distilled off, in which copper dissolves; the last transformation is accompanied by the evolution of brown gas and the formation of a copper salt. During the thermal decomposition of both salts, oxygen is one of the decomposition products. Write down the equations for the reactions described.

The substance obtained at the anode during the electrolysis of sodium iodide melt with inert electrodes was isolated and introduced into interaction with hydrogen sulfide. The gaseous product of the last reaction was dissolved in water and ferric chloride was added to the resulting solution. The formed precipitate was filtered off and treated with hot sodium hydroxide solution. Write down the equations for the reactions described.

The gases that are released when coal is heated in concentrated nitric and sulfuric acids are mixed with each other. The reaction products were passed through milk of lime. Write down the equations for the reactions described.

A mixture of iron powder and a solid product obtained by the interaction of sulfur dioxide and hydrogen sulfide was heated without access to air. The resulting product was calcined in air. The resulting solid reacts with aluminum to generate a large amount of heat. Write down the equations for the reactions described.

A black substance was obtained by calcining the precipitate that forms during the interaction of solutions of sodium hydroxide and copper (II) sulfate. When this substance is heated with coal, a red metal is obtained, which dissolves in concentrated sulfuric acid. Write down the equations for the reactions described.

A simple substance, a mixture of which with berthollet's salt is used in matches and ignites upon friction, was burned in excess of oxygen. The white solid from the combustion was dissolved in an excess of sodium hydroxide solution. The resulting salt with a solution of silver nitrate forms a bright yellow precipitate. Write down the equations for the reactions described.

The zinc was dissolved in very dilute nitric acid and an excess of alkali was added to the resulting solution to give a clear solution. Write down the equations for the reactions described.

The solution obtained by passing sulfur dioxide through bromine water was neutralized with barium hydroxide. The formed precipitate was separated, mixed with coke and calcined. When processing the calcined product with hydrochloric acid, a gas with the smell of rotten eggs is released. Write down the equations for the reactions described.

The substance formed by adding zinc powder to the ferric chloride solution was separated by filtration and dissolved in hot dilute nitric acid. The solution was evaporated, the solid residue was calcined, and the evolved gases were passed through a sodium hydroxide solution. Write down the equations for the reactions described.

The gas evolved upon heating a solution of hydrogen chloride with manganese (IV) oxide was introduced into interaction with aluminum. The reaction product was dissolved in water and first an excess of sodium hydroxide solution was added, and then hydrochloric acid (excess). Write down the equations for the reactions described.

A mixture of two colorless, colorless and odorless gases A and B was passed while heating over a catalyst containing iron, and the resulting gas B neutralized a solution of hydrobromic acid. The solution was evaporated and the residue was heated with caustic potash, resulting in the evolution of colorless gas B with a pungent odor. When gas B is burned in air, water and gas A are formed. Write the equations for the described reactions.

Sulfur dioxide was passed through a hydrogen peroxide solution. Water was evaporated from the resulting solution and magnesium turnings were added to the residue. The evolved gas was passed through a solution of copper sulfate. The precipitated black precipitate was separated and fired. Write down the equations for the reactions described.

A solution of hydrochloric acid was added to the water-insoluble white salt, which occurs in nature in the form of a mineral widely used in construction and architecture, as a result, the salt dissolved and gas was released, when passed through lime water, a white precipitate was formed, which dissolved later passing gas. When an excess of lime water is added to the resulting solution, a precipitate forms. Write down the equations for the reactions described.

When some mineral A, consisting of two elements, is fired, a gas is formed that has a characteristic pungent odor and decolorizes bromine water with the formation of two strong acids in solution. When substance B, consisting of the same elements as mineral A, but in a different ratio, interacts with concentrated hydrochloric acid, a poisonous gas with the smell of rotten eggs is released. When the released gases interact with each other, a simple yellow substance and water are formed. Write down the equations for the reactions described.

The substance released at the cathode during the electrolysis of the sodium chloride melt was burned in oxygen. The resulting product was placed in a gas meter filled with carbon dioxide. The resulting substance was added to the ammonium chloride solution and the solution was heated. Write down the equations for the reactions described.

The nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was calcined. The resulting substance was introduced into a solution of potassium permanganate acidified with sulfuric acid, and the solution became discolored. The nitrogen-containing reaction product was placed in a sodium hydroxide solution and zinc dust was added, while a gas with a pungent characteristic odor was released. Write down the equations for the reactions described.

When a solution of salt A interacted with alkali, a gelatinous water-insoluble blue substance was obtained, which was dissolved in colorless liquid B to form a blue solution. The solid product remaining after careful evaporation of the solution was calcined; At the same time, two gases were released, one of which is brown, and the second is part of the atmospheric air, and a black solid remains, which dissolves in liquid B with the formation of substance A. Write the equations for the described reactions.

White phosphorus dissolves in a solution of caustic potash, producing a garlic-smelling gas that ignites spontaneously in air. The solid product of the combustion reaction reacted with sodium hydroxide in such a ratio that the resulting white substance contains one hydrogen atom; when the latter is ignited, sodium pyrophosphate is formed. Write down the equations for the reactions described.

The solution of ferric chloride was treated with sodium hydroxide solution, the precipitate that formed was separated and heated. The solid reaction product was mixed with soda ash and calcined. Both sodium nitrate and sodium hydroxide were added to the remaining substance and heated for a long time at a high temperature. Write down the equations for the reactions described.

The gas released during the interaction of hydrogen chloride with potassium permanganate was passed through a solution of sodium tetrahydroxoaluminate. The formed precipitate was filtered off, calcined, and the solid residue was treated with hydrochloric acid. Write down the equations for the reactions described.

The nitrogen-hydrogen mixture was heated to a temperature of 500 ° C and passed under high pressure over an iron catalyst. The reaction products were passed through a nitric acid solution until it was neutralized. The resulting solution was carefully evaporated, the solid residue was calcined, and the gas evolved during this process was passed over copper while heating, resulting in a black solid. Write down the equations for the reactions described.

Trivalent chromium hydroxide was treated with hydrochloric acid. Potash was added to the resulting solution, the separated precipitate was separated and introduced into a concentrated solution of potassium hydroxide, as a result the precipitate was dissolved. After adding an excess of hydrochloric acid, a green solution was obtained. Write down the equations for the reactions described.

The substance obtained at the anode during the electrolysis of a sodium iodide solution with inert electrodes was reacted with potassium. The reaction product was heated with concentrated sulfuric acid and the evolved gas was passed through a hot potassium chromate solution. Write down the equations for the reactions described.

Ferrous oxide was heated with dilute nitric acid. The solution was carefully evaporated, the solid residue was dissolved in water, iron powder was added to the resulting solution, and after a while it was filtered. A solution of potassium hydroxide was added to the filtrate, the precipitate that formed was separated and left in air, while the color of the substance changed. Write down the equations for the reactions described.

One of the substances formed by the fusion of silicon oxide with magnesium dissolves in alkali. The evolved gas was reacted with sulfur, and the product of their interaction was treated with chlorine. Write down the equations for the reactions described.

The solid substance formed by the interaction of sulfur dioxide and hydrogen sulfide, when heated, interacts with aluminum. The reaction product was dissolved in dilute sulfuric acid, and potash was added to the resulting solution. Write down the equations for the reactions described.

An unknown metal was burned in oxygen. The reaction product, interacting with carbon dioxide, forms two substances: a solid, which interacts with a hydrochloric acid solution with the release of carbon dioxide, and a gaseous simple substance that supports combustion. Write down the equations for the reactions described.

The product of the interaction of nitrogen and lithium was treated with water. The gas evolved as a result of the reaction was mixed with an excess of oxygen and, when heated, passed over a platinum catalyst; the resulting gas mixture had a brown color. Write down the equations for the reactions described.

The copper shavings were dissolved in dilute nitric acid and the solution was neutralized with caustic potassium. The liberated blue substance was separated, calcined (the color of the substance changed to black), mixed with coke and re-calcined. Write down the equations for the reactions described.

The phosphorus was burned in excess of chlorine, the resulting solid was mixed with phosphorus and heated. The reaction product was treated with water, while a colorless gas with a pungent odor evolved. The solution was added to a solution of potassium permanganate acidified with sulfuric acid, which became colorless as a result of the reaction. Write down the equations for the reactions described.

The ferric chloride was treated with concentrated nitric acid while heating and the solution was carefully evaporated. The solid product was dissolved in water, potash was added to the resulting solution, and the precipitate formed was separated and calcined. Hydrogen gas was passed over the obtained substance while heating. Write down the equations for the reactions described.

An unknown salt, when interacting with a silver nitrate solution, forms a white precipitate and colors the burner flame yellow. When concentrated sulfuric acid interacts with this salt, a poisonous gas is formed, which is highly soluble in water. Iron dissolves in the resulting solution, and a very light colorless gas is released, which is used to obtain metals, such as copper, from their oxides. Write down the equations for the reactions described.

The magnesium silicide was treated with a solution of hydrochloric acid and the evolved gas was burned. The solid reaction product was mixed with soda ash, the mixture was heated to melting and held for some time. After cooling, the reaction product (commonly known as “liquid glass”) was dissolved in water and treated with a sulfuric acid solution. Write down the equations for the reactions described.

A gas mixture of ammonia and a large excess of air was passed while heating over platinum, and after a while the reaction products were absorbed in a sodium hydroxide solution. After evaporation of the solution, a single product was obtained. Write down the equations for the reactions described.

Soda ash was added to the ferric chloride solution, and the precipitate formed was separated and calcined. Carbon monoxide was passed over the resulting substance while heating and the solid product of the last reaction was introduced into interaction with bromine. Write down the equations for the reactions described.

The product of the interaction of sulfur with aluminum (the reaction proceeds when heated) was dissolved in cold dilute sulfuric acid and potassium carbonate was added to the solution. The formed precipitate was separated, mixed with sodium hydroxide and heated. Write down the equations for the reactions described.

Silicon (IV) chloride was heated in a mixture with hydrogen. The reaction product was mixed with magnesium powder, heated and treated with water; one of the resulting substances ignites spontaneously in air. Write down the equations for the reactions described.

Brown gas was passed through the excess potassium hydroxide solution in the presence of a large excess of air. Magnesium shavings were added to the resulting solution and heated; the released gas neutralized nitric acid. The resulting solution was carefully evaporated, and the solid reaction product was calcined. Write down the equations for the reactions described.

Iron oxide was dissolved in concentrated nitric acid with heating. The solution was carefully evaporated and the reaction product was dissolved in water. Iron powder was added to the resulting solution, after a while the solution was filtered and the filtrate was treated with a potassium hydroxide solution; as a result, a light green precipitate was formed, which quickly darkened in air. Write down the equations for the reactions described.

To a solution of soda ash was added a solution of aluminum chloride, the separated substance was separated and introduced into the sodium hydroxide solution. A solution of hydrochloric acid was added dropwise to the resulting solution until the formation of a precipitate ceased, which was separated and calcined. Write down the equations for the reactions described.

Copper shavings were added to the mercury (II) nitrate solution. After the end of the reaction, the solution was filtered and the filtrate was added dropwise to a solution containing sodium hydroxide and ammonium hydroxide. In this case, a short-term formation of a precipitate was observed, which dissolved with the formation of a bright blue solution. When an excess of sulfuric acid solution was added to the resulting solution, a color change occurred. Write down the equations for the reactions described.

The reaction product of magnesium phosphide with water was burned and the reaction products were absorbed in water. The resulting substance is used in industry to obtain double superphosphate from phosphorite. Write down the equations for the reactions described.

The salt obtained by reacting zinc oxide with sulfuric acid was calcined at 800 ° C. The solid reaction product was treated with a concentrated alkali solution and carbon dioxide was passed through the resulting solution. Write the reaction equations for the described transformations.

Iron powder was added to the ferric chloride solution and after a while the solution was filtered. Sodium hydroxide was added to the filtrate, the separated precipitate was separated and treated with hydrogen peroxide. An excess of potassium hydroxide and bromine solution was added to the resulting substance; as a result of the reaction, the color of bromine disappeared. Write down the equations for the reactions described.

Copper (I) oxide was treated with concentrated nitric acid, the solution was carefully evaporated, and the solid residue was calcined. The gaseous reaction products were passed through a large amount of water and magnesium chips were added to the resulting solution, resulting in the release of a gas used in medicine. Write down the equations for the reactions described.

Sulfur dioxide was passed through a hydrogen peroxide solution. The solution was evaporated and copper shavings were added to the remaining liquid. The evolved gas was mixed with the gas that forms when iron (II) sulfide interacts with a solution of hydrobromic acid. Write down the equations for the reactions described.

When a yellow salt, which turns the flame purple, and dilute hydrochloric acid, was added to the solution, the color changed to orange-red. After neutralizing the solution with concentrated alkali, the color of the solution returned to its original color. When barium chloride is added to the resulting solution, a yellow precipitate forms. The precipitate was filtered off and silver nitrate solution was added to the filtrate. Write down the equations for the reactions described.

Magnesium silicide was treated with a solution of hydrochloric acid, the reaction product was burned, the resulting solid was mixed with soda ash and heated to melting. After cooling the melt, it was treated with water and nitric acid was added to the resulting solution. Write down the equations for the reactions described.

The insoluble substance formed by adding sodium hydroxide to the ferric chloride solution was separated and dissolved in dilute sulfuric acid. Zinc dust was added to the resulting solution, the separated precipitate was filtered off and dissolved in concentrated hydrochloric acid. Write down the equations for the reactions described.

Aluminum nitrate was calcined, the reaction product was mixed with soda ash and heated to melting. The resulting substance was dissolved in nitric acid and the resulting solution was neutralized with an ammonia solution, while the formation of a bulky gelatinous precipitate was observed. Write down the equations for the reactions described.

Magnesium nitride was treated with excess water. When the evolved gas is passed both through bromine water or through a neutral solution of potassium permanganate, and when it is burned, the same gaseous product is formed. Write down the equations for the reactions described.

Chlorine water smells like chlorine. When alkalinized, the smell disappears, and when hydrochloric acid is added, it becomes stronger than it was before. Write down the equations for the reactions described.

The solid substance formed by heating malachite was heated in a hydrogen atmosphere. The reaction product was treated with concentrated sulfuric acid and, after separation from sulfuric acid, was introduced into a sodium chloride solution containing copper filings, and as a result a precipitate formed. Write down the equations for the reactions described.

Phosphine was passed through a hot solution of concentrated nitric acid. The solution was neutralized with quicklime, the precipitate formed was separated, mixed with coke and silica and calcined. The reaction product, which glows in air, was heated in a sodium hydroxide solution. Write down the equations for the reactions described.

The iron powder was dissolved in a large amount of dilute sulfuric acid, and air was passed through the resulting solution, and then a gas with the smell of rotten eggs was passed. The formed insoluble salt was separated and dissolved in a hot solution of concentrated nitric acid. Write down the equations for the reactions described.

Colorless gases are released when concentrated sulfuric acid is kept with both sodium chloride and sodium iodide. When these gases are passed through an aqueous ammonia solution, salts are formed. Write down the equations for the reactions described.

The magnesium powder was mixed with silicon and heated. The reaction product was treated with cold water and the evolved gas was passed through hot water. The formed precipitate was separated, mixed with sodium hydroxide and heated to melting. Write down the equations for the reactions described.

One of the products of the interaction of ammonia with bromine - a gas that is part of the atmosphere, was mixed with hydrogen and heated in the presence of platinum. The resulting gas mixture was passed through a hydrochloric acid solution and potassium nitrite was added to the resulting solution with slight heating. Write down the equations for the reactions described.

The salt obtained by dissolving copper in dilute nitric acid was electrolyzed using graphite electrodes. The substance released at the anode was brought into interaction with sodium, and the resulting reaction product was placed in a vessel with carbon dioxide. Write down the equations for the reactions described.

Unknown substance A dissolves in concentrated hydrochloric acid, the dissolution process is accompanied by the release of gas with the smell of rotten eggs; after neutralization of the solution with alkali, a voluminous white (light green) precipitate is formed. When substance A is fired, two oxides are formed. One of them is a gas that has a characteristic pungent odor and decolorizes bromine water with the formation of two strong acids in solution. Write down the equations for the reactions described.

Magnesium was heated in a vessel filled with gaseous ammonia. The resulting substance was dissolved in a concentrated solution of hydrobromic acid, the solution was evaporated and the residue was heated until an odor appeared, after which an alkali solution was added. Write down the equations for the reactions described.

Soda ash was added to the trivalent chromium sulfate solution. The separated precipitate was separated, transferred to a sodium hydroxide solution, bromine was added and heated. After neutralization of the reaction products with sulfuric acid, the solution acquires an orange color, which disappears after passing sulfur dioxide through the solution. Write down the equations for the reactions described.

Quicklime was calcined with an excess of coke. The reaction product after treatment with water is used to absorb sulfur dioxide and carbon dioxide. Write down the equations for the reactions described.

The sulfide of ferrous iron was treated with a solution of hydrochloric acid, the released gas was collected and burned in the air. The reaction products were passed through an excess of potassium hydroxide solution, after which a solution of potassium permanganate was added to the resulting solution. Write down the equations for the reactions described.

The solid product of the thermal decomposition of malachite was dissolved by heating in concentrated nitric acid. The solution was carefully evaporated and the solid residue was calcined to give a black substance, which was heated in excess of ammonia (gas). Write down the equations for the reactions described.

Red phosphorus was burned in a chlorine atmosphere. The reaction product was treated with excess water and powdered zinc was added to the solution. The evolved gas was passed over heated ferrous oxide. Write the reaction equations for the described transformations.

A silvery-gray metal, which is attracted by a magnet, was added to hot concentrated sulfuric acid and heated. The solution was cooled and sodium hydroxide was added until the formation of an amorphous brown precipitate ceased. The precipitate was separated, calcined, and dissolved in concentrated hydrochloric acid while heating. Write down the equations for the reactions described.

Magnesium shavings were heated in a nitrogen atmosphere, and the reaction product was sequentially treated with boiling water, solutions of sulfuric acid and barium nitrate. Write down the equations for the reactions described.

The thermal decomposition of salt A in the presence of manganese dioxide resulted in the formation of binary salt B and a gas that supports combustion and is part of the air; when this salt is heated without a catalyst, salt B and a salt of a higher oxygen-containing acid are formed. When salt A interacts with hydrochloric acid, a yellow-green poisonous gas (a simple substance) is released and salt B is formed. Salt B colors the flame purple; when it interacts with a solution of silver nitrate, a white precipitate forms. Write down the equations for the reactions described.

The precipitate obtained by adding caustic soda to the aluminum sulfate solution was separated, calcined, mixed with soda ash and heated to melting. After treating the residue with sulfuric acid, the starting aluminum salt was obtained. Write down the equations for the reactions described.

The substance formed during the fusion of magnesium with silicon was treated with water, as a result of which a precipitate formed and a colorless gas evolved. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate, with the formation of two water-insoluble binary substances. Write down the equations for the reactions described.

The substance obtained by heating iron scale in a hydrogen atmosphere was introduced into hot concentrated sulfuric acid and heated. The resulting solution was evaporated, the residue was dissolved in water and treated with a solution of barium chloride. The solution was filtered and a copper plate was introduced into the filtrate, which after a while dissolved. Write down the equations for the reactions described.

Quicklime was "quenched" with water. A gas was passed into the resulting solution, which is released during the calcination of sodium bicarbonate, while the formation and subsequent dissolution of the precipitate was observed. Write down the equations for the reactions described.

A mixture of nitrogen and hydrogen was sequentially passed over heated platinum and through a sulfuric acid solution. Barium chloride was added to the solution and, after separating the precipitated sediment, milk of lime was added and heated. Write down the equations for the reactions described.

Give examples of interaction:

two acids

two reasons

two acidic salts

two acidic oxides

Write down the equations for the reactions described.

A solution of a medium salt formed by passing a sulfur dioxide gas through an alkali solution was left in air for a long time. The solid formed after the solution was evaporated was mixed with coke and heated to a high temperature. When hydrochloric acid is added to the solid product of the reaction, a gas with the smell of rotten eggs is released. Write down the equations for the reactions described.

A solution of dilute sulfuric acid was added to the black powdery substance and heated. A solution of sodium hydroxide was poured into the resulting blue solution until the precipitation ceased. The precipitate was filtered off and heated. The reaction product was heated under a hydrogen atmosphere to give a red solid. Write down the equations for the reactions described.

Red phosphorus was burned in a chlorine atmosphere and a small amount (a few drops) of water was added to the reaction product. The liberated substance was dissolved in an excess of water, iron powder was added to the resulting solution, and the gaseous reaction product was passed over a heated copper plate oxidized to bivalent copper oxide. Write the reaction equations for the described transformations.

The iron (III) chloride solution was electrolyzed with graphite electrodes. The brown precipitate formed during electrolysis was filtered off and dissolved in a sodium hydroxide solution, after which an amount of sulfuric acid was added, which was necessary to form a clear solution. The product released at the anode was passed through a hot potassium hydroxide solution. Write down the equations for the reactions described.

Aluminum chloride was added to the crystalline soda solution, the separated precipitate was separated and treated with sodium hydroxide solution. The resulting solution was neutralized with nitric acid, the separated precipitate was separated and calcined. Write down the equations for the reactions described.

Ammonia was mixed with a large excess of air, heated in the presence of platinum, and after a while absorbed in water. Copper shavings added to the resulting solution dissolve with the release of brown gas. Write down the equations for the reactions described.

When a solution of acid A is added to manganese dioxide, a poisonous gas of yellow-green color is released. Having passed the released gas through a hot solution of caustic potassium, a substance is obtained that is used in the manufacture of matches and some other incendiary compositions. During the thermal decomposition of the latter in the presence of manganese dioxide, a salt is formed, from which, when interacting with concentrated sulfuric acid, it is possible to obtain the original acid A, and a colorless gas included in the composition of atmospheric air. Write down the equations for the reactions described.

The product of the interaction of silicon with chlorine is easily hydrolyzed. When a solid hydrolysis product fusion with both caustic and soda ash, water glass is formed. Write down the equations for the reactions described.

To the solution obtained by dissolving iron in hot concentrated hydrochloric acid, sodium hydroxide was added. The separated precipitate was separated, left in air for a long time, and then dissolved in dilute hydrochloric acid. Write down the equations for the reactions described.

When heated, the orange-colored substance decomposes; Decomposition products include a colorless gas and a green solid. The released gas reacts with lithium even when heated slightly. The product of the last reaction interacts with water, while a gas with a pungent odor is released, which can reduce metals, such as copper, from their oxides. Write down the equations for the reactions described.

A rotten egg smell gas was passed through concentrated sulfuric acid at room temperature. The formed precipitate was separated and treated with hot concentrated nitric acid; the evolved gas was dissolved in a large amount of water and a piece of copper was added to the resulting solution. Write the reaction equations for the described transformations.

The salt obtained by dissolving iron in hot concentrated sulfuric acid was treated with an excess of sodium hydroxide solution. The resulting brown precipitate was filtered off and calcined. The resulting substance was fused with iron. Write down the equations for the reactions described.

Metallic zinc was added to concentrated sulfuric acid. The resulting salt was isolated, dissolved in water, and barium nitrate was added to the solution. After separating the precipitate, magnesium chips were introduced into the solution, the solution was filtered, the filtrate was evaporated and calcined. Write down the equations for the reactions described.

The unknown red substance was heated in chlorine and the reaction product was dissolved in water. An alkali was added to the resulting solution, the precipitated blue precipitate was filtered off and calcined. On heating the black calcined product, a red starting material was obtained with coke. Write down the equations for the reactions described.

Iodine was heated with excess phosphorus and the reaction product was treated with a small amount of water. The gaseous reaction product was completely neutralized with sodium hydroxide solution and silver nitrate was added to the resulting solution. Write down the equations for the reactions described.

The iron was burned in chlorine. The reaction product was dissolved in water and iron filings were added to the solution. After a while, the solution was filtered and sodium sulfide was added to the filtrate. The separated precipitate was separated and treated with 20% sulfuric acid, obtaining an almost colorless solution. Write down the equations for the reactions described.

The gas evolved when heating solid sodium chloride with concentrated sulfuric acid was passed through a solution of potassium permanganate. The gaseous reaction product was taken up in a cold sodium hydroxide solution. After adding hydroiodic acid to the resulting solution, a pungent odor appears and the solution becomes dark in color. Write down the equations for the reactions described.

Through the solution obtained by slaking lime, gas was passed, which is formed when obtaining quicklime from limestone; the result is a white precipitate. When acetic acid acts on the resulting precipitate, the same gas is released, which is formed when calcining calcium carbonate. Write down the equations for the reactions described.

The red substance, which is used in the manufacture of matches, was burned in excess air and the reaction product was dissolved in a large amount of water when heated. After neutralizing the resulting solution with baking soda, silver nitrate was added to it. Write down the equations for the reactions described.

Through the sodium bromide solution, the gas evolved from the interaction of hydrochloric acid with potassium permanganate was passed. After the end of the reaction, the solution was evaporated, the residue was dissolved in water and subjected to electrolysis with graphite electrodes. The gaseous reaction products were mixed with each other and illuminated, and the result was an explosion. Write down the equations for the reactions described.

The gas formed during the combustion of coke was in contact with hot coal for a long time. The reaction product was subsequently passed through a layer of heated iron ore and quicklime. Write down the equations for the reactions described.

Copper shavings were added to heated concentrated sulfuric acid, and the released gas was passed through a sodium hydroxide solution (excess). The reaction product was isolated, dissolved in water and heated with sulfur, which was dissolved as a result of the reaction. Dilute sulfuric acid was added to the resulting solution. Write down the equations for the reactions described.

Hydrochloric acid was added to solutions of substances L and B, which color the flame yellow: When a solution of substance A interacts with hydrochloric acid, a colorless gas with an unpleasant odor is released, which forms a black precipitate when lead (II) nitrate is passed through the solution. When a solution of substance B with hydrochloric acid is heated, the color of the solution changes from yellow to green, and a poisonous gas of yellow-green color with a characteristic pungent odor is released. When barium nitrate is added to the solution of substance B, a yellow precipitate forms. Write down the equations for the reactions described.

A solution of hydrochloric acid was carefully added to the pyrolusite, and the evolved gas was passed into a beaker half filled with a cold solution of potassium hydroxide. After the end of the reaction, the glass was covered with a cardboard and left, while the glass was illuminated by the sun's rays; after a while, a smoldering splinter was brought into the glass, which flashed brightly. Write down the equations for the reactions described.

The precipitate obtained by the interaction of a solution of an aluminum salt and an alkali was calcined. The reaction product was dissolved in a concentrated hot alkali solution. Carbon dioxide was passed through the resulting solution, resulting in the formation of a precipitate. Write the equations for the described transformations.

The black powder, which was formed upon prolonged heating of the red metal in excess air, was dissolved in 10% sulfuric acid and a blue solution was obtained. Alkali was added to the solution, and the precipitate formed was separated and dissolved in an excess of ammonia solution. Write down the equations for the reactions described.

Phosphorus was added to the solid matter that forms when phosphorus is burned in excess of chlorine and the mixture was heated. The reaction product was treated with a small amount of hot water and a solution of potassium permanganate acidified with sulfuric acid was added to the resulting solution. Write down the equations for the reactions described.

Carbon dioxide was passed through barite water. Barium hydroxide was added to the resulting solution, the reaction product was separated and dissolved in phosphoric acid. Write down the equations for the reactions described.

Zinc nitrate was calcined, and the reaction product was treated with sodium hydroxide solution while heating. Carbon dioxide was passed through the resulting solution until the precipitation ceased, after which it was treated with an excess of concentrated ammonia, and the precipitate dissolved. Write down the equations for the reactions described.

Two vessels contain solutions of unknown substances. When barium chloride is added to the solution of the first substance, a white precipitate is formed, insoluble in water and acids. A white precipitate also falls out when the silver nitrate solution is added to the sample taken from the second vessel. When the sample of the first solution with sodium hydroxide is heated, a pungent odor is emitted into the gas. When the second solution interacts with sodium chromate, a yellow precipitate forms. Write down the equations for the reactions described.

Sulfur dioxide was dissolved in water and the solution was neutralized by adding sodium hydroxide. Hydrogen peroxide was added to the resulting solution, and after the end of the reaction, sulfuric acid was added. Write down the equations for the reactions described.

The zinc was dissolved in very dilute nitric acid, the resulting solution was carefully evaporated and the residue was calcined. The reaction products were mixed with coke and heated. Make up the reaction equations for the described transformations.

Substances released at the cathode and anode during the electrolysis of sodium iodide solution with graphite electrodes react with each other. The reaction product interacts with concentrated sulfuric acid with the evolution of gas, which was passed through a potassium hydroxide solution. Write down the equations for the reactions described.

The substance, which is formed during the electrolysis of bauxite melt in cryolite, dissolves both in a hydrochloric acid solution and in an alkali solution with the release of the same gas. When the resulting solutions are mixed, a white bulk precipitate is formed. Write down the equations for the reactions described.

Concentrated hydrochloric acid was added to lead (IV) oxide with heating. The evolved gas was passed through a heated potassium hydroxide solution. The solution was cooled, the oxygenate acid salt was filtered off and dried. When the resulting salt is heated with hydrochloric acid, a poisonous gas is released, and when heated in the presence of manganese dioxide, the gas is included and the composition of the atmosphere. Write down the equations for the reactions described.

The brown precipitate obtained by the interaction of sodium sulfite with an aqueous solution of potassium permanganate was filtered off and treated with concentrated sulfuric acid. The evolved gas when heated reacts with aluminum, and the resulting substance - with a solution of hydrochloric acid. Write the reaction equations for the described transformations.

Calcium was heated in a hydrogen atmosphere. The reaction product was treated with water, the evolved gas was passed over heated zinc oxide, and soda ash was added to the solution. Write down the equations for the reactions described.

Silver nitrate was calcined and the solid reaction product was heated in oxygen. The resulting substance is dissolved in an excess of concentrated ammonia. When passing through the resulting solution of hydrogen sulfide, a black precipitate is formed. Write down the equations for the reactions described.

The solid substance, which is formed by heating phosphorus and phosphorus pentachloride, was dissolved in a large amount of water. Part of the resulting solution was added to a solution of potassium permanganate acidified with sulfuric acid, the latter discolored. Write down the equations for the reactions described.

Several zinc granules were introduced into a vessel with concentrated sulfuric acid. The evolved gas was passed through a solution of lead (II) acetate, the precipitate was separated, subjected to roasting, and the resulting gas was brought into interaction with an aqueous solution of potassium permanganate. Write down the equations for the reactions described.

Several zinc granules were dissolved by heating in a sodium hydroxide solution. Nitric acid was added to the resulting solution in small portions until a precipitate was formed. The precipitate was separated, dissolved in dilute nitric acid, the solution was carefully evaporated, and the residue was calcined. Write down the equations for the reactions described.

The gas released during the dissolution of copper in hot concentrated nitric acid can interact with both the gas released during the treatment of copper with hot concentrated sulfuric acid and with copper. Write down the equations for the reactions described.

The iron (III) chloride solution was electrolyzed with graphite electrodes. The separated brown precipitate (a by-product of electrolysis) was filtered off, calcined, and fused with the substance formed at the cathode. Another substance, also released at the cathode, was introduced into a reaction with the product released during electrolysis at the anode; the reaction proceeds under illumination and with an explosion. Write down the equations for the reactions described.

Water-insoluble white salt that meets ­ It occurs in nature in the form of a mineral widely used in construction and architecture, calcined at 1000 ° C. After cooling, water was added to the solid residue, and the gaseous product of the decomposition reaction was passed through the resulting solution; as a result, a white precipitate was formed, which dissolved upon further passing the gas. Write down the equations for the reactions described.