Why is co2 acidic oxide. Acid oxides: a brief description of the group

Everything chemical compounds existing in nature are divided into organic and inorganic. Among the latter, the following classes are distinguished: oxides, hydroxides, salts. Hydroxides are classified into bases, acids, and amphoteric. Among the oxides, acidic, basic and amphoteric ones can also be distinguished. Substances of the latter group can exhibit both acidic and basic properties.

Chemical properties of acidic oxides

Such substances have peculiar Chemical properties... Acidic oxides are capable of entering into chemical reactions only with basic hydroxides and oxides. This group of chemical compounds includes substances such as carbon dioxide, sulfur dioxide and trioxide, chromium trioxide, manganese heptaoxide, phosphorus pentoxide, chlorine trioxide and pentoxide, nitrogen tetra- and pentoxide, silicon dioxide.

Substances of this kind are also called anhydrides. The acidic properties of oxides are manifested primarily during their reactions with water. This produces a certain oxygen-containing acid. For example, if we take sulfur trioxide and water in equal amounts, we get sulfate (sulfuric) acid. Phosphoric acid can be synthesized in the same way by adding water to phosphorus oxide. Reaction equation: P2O5 + 3H2O = 2H3PO4. In exactly the same way, it is possible to obtain acids such as nitrate, silicic, etc. Also acidic oxides enter into chemical interaction with basic or amphoteric hydroxides. During these reactions, salt and water are formed. For example, if you take sulfur trioxide and add calcium hydroxide to it, you get calcium sulfate and water. If we add zinc hydroxide, we get zinc sulfate and water. Another group of substances with which these chemical compounds interact are basic and amphoteric oxides. When reacting with them, only salt is formed, without water. For example, adding amphoteric alumina to sulfur trioxide produces aluminum sulfate. And if you mix silicon oxide with basic calcium oxide, you get calcium silicate. In addition, acidic oxides react with basic and normal salts. When reacting with the latter, acidic salts... For example, if calcium carbonate and water are added to carbon dioxide, calcium bicarbonate can be obtained. Reaction equation: CO 2 + CaCO 3 + H 2 O = Ca (HCO 3) 2. When acid oxides react with basic salts, normal salts are formed.

Substances of this group do not interact with acids and other acidic oxides. Amphoteric oxides are also capable of exhibiting exactly the same chemical properties, except that they also interact with acid oxides and hydroxides, that is, they combine both acidic and basic properties.

Physical properties and applications of acidic oxides

There are quite a few different physical properties acid oxides, so it is possible to use them in the most different areas industry.

Sulfur trioxide

Most often, this compound is used in the chemical industry. It is an intermediate product formed during the production of sulfate acid. This process consists in the fact that iron pyrite is burned, thus obtaining sulfur dioxide, then the latter is subjected to a chemical reaction with oxygen, as a result of which trioxide is formed. Further, sulfuric acid is synthesized from the trioxide by adding water to it. Under normal conditions, this substance is a colorless liquid with unpleasant odor... At temperatures below sixteen degrees Celsius, sulfur trioxide solidifies, forming crystals.

Phosphorus pentoxide

Acidic oxides also include phosphorus pentoxide. It is a white snow-like substance. It is used as a dehydrating agent due to the fact that it very actively interacts with water, while forming phosphoric acid (it is also used in chemical industry to get it).

Carbon dioxide

It is the most abundant acid oxide in nature. The content of this gas in the composition of the Earth's atmosphere is about one percent. Under normal conditions, this substance is a colorless and odorless gas. Carbon dioxide is widely used in Food Industry: for the production of carbonated drinks, as a baking powder, as a preservative (under the designation E290). Liquefied carbon dioxide is used to make fire extinguishers. Also, this substance plays huge role in nature - for photosynthesis, as a result of which oxygen, vital for animals, is formed. Plants need exactly carbon dioxide. This substance is released during the combustion of all organic chemical compounds without exception.

Silica

Under normal conditions, it appears as colorless crystals. In nature, it can be found in the form of many different minerals such as quartz, crystal, chalcedony, jasper, topaz, amethyst, morion. This acidic oxide is actively used in the production of ceramics, glass, abrasive materials, concrete products, fiber-optic cables. Also, this substance is used in radio engineering. In the food industry, it is used in the form of an additive, encrypted under the name E551. Here it is used to maintain the original shape and consistency of the product. This food additive can be found, for example, in instant coffee... In addition, silicon dioxide is used in the manufacture of toothpastes.

Manganese heptaoxide

This substance is a brownish-green mass. It is used mainly for the synthesis of manganic acid by adding water to the oxide.

Nitrogen Pentoxide

It is a solid, colorless substance in the form of crystals. It is used in most cases in the chemical industry to obtain nitric acid or other nitrogen oxides.

Chlorine trioxide and tetroxide

The first is a green-yellow gas, the second is a liquid of the same color. They are used mainly in the chemical industry to obtain the corresponding chlorous acids.

Getting acidic oxides

Substances of this group can be obtained due to the decomposition of acids under the influence of high temperatures... In this case, the desired substance and water are formed. Examples of reactions: H 2 CO 3 = H 2 O + CO 2; 2H 3 PO 4 = 3H 2 O + P 2 O 5. Manganese heptaoxide can be obtained by exposure to potassium permanganate concentrated solution sulfate acid. This reaction produces the desired substance, potassium sulfate and water. Carbon dioxide can be obtained from decomposition carboxylic acid, interaction of carbonates and hydrocarbonates with acids, reactions baking soda with citric acid.

Conclusion

Summing up everything written above, we can say that acid oxides are widely used in the chemical industry. Only a few of them are also used in the food and other industries.

Acidic oxides are large group inorganic chemical compounds that have great importance and can be used to obtain a wide variety of oxygenated acids. This group also includes two important substances: carbon dioxide and silicon dioxide, the first of which plays a huge role in nature, and the second is presented in the form of many minerals that are often used in the manufacture of jewelry.

Oxides.

It - complex substances consisting of TWO elements, one of which is oxygen. For example:

CuO - copper (II) oxide

AI 2 O 3 - aluminum oxide

SO 3 - sulfur oxide (VI)

Oxides are divided (classified) into 4 groups:

Na 2 O - Sodium oxide

CaO - Calcium oxide

Fe 2 O 3 - iron (III) oxide

2). Acidic- These are oxides non-metals... And sometimes metals if the oxidation state of the metal is> 4. For example:

CO 2 - Carbon monoxide (IV)

Р 2 О 5 - Phosphorus (V) oxide

SO 3 - Sulfur oxide (VI)

3). Amphoteric- These are oxides that have the properties of both basic and acidic oxides. You need to know the five most common amphoteric oxides:

BeO – beryllium oxide

ZnO - Zinc oxide

AI 2 O 3 - Aluminum oxide

Cr 2 O 3 - Chromium (III) oxide

Fe 2 O 3 - Iron (III) oxide

4). Non-salt-forming (indifferent)- These are oxides that do not exhibit the properties of either basic or acidic oxides. There are three oxides to remember:

CO - carbon monoxide (II) carbon monoxide

NO - nitric oxide (II)

N 2 O - nitric oxide (I) laughing gas, nitrous oxide

Methods for producing oxides.

1). Combustion, i.e. interaction with oxygen of a simple substance:

4Na + O 2 = 2Na 2 O

4P + 5O 2 = 2P 2 O 5

2). Combustion, i.e. interaction with oxygen of a complex substance (consisting of two elements) in this case, two oxides.

2ZnS + 3O 2 = 2ZnO + 2SO 2

4FeS 2 + 11O 2 = 2Fe 2 O 3 + 8SO 2

3). Decomposition three weak acids. Others do not decompose. In this case, acidic oxide and water are formed.

H 2 CO 3 = H 2 O + CO 2

H 2 SO 3 = H 2 O + SO 2

H 2 SiO 3 = H 2 O + SiO 2

4). Decomposition insoluble grounds. Basic oxide and water are formed.

Mg (OH) 2 = MgO + H 2 O

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

5). Decomposition insoluble salts. A basic oxide and an acidic oxide are formed.

CaCO 3 = CaO + CO 2

MgSO 3 = MgO + SO 2

Chemical properties.

I... Basic oxides.

alkali.

Na 2 O + H 2 O = 2NaOH

CaO + H 2 O = Ca (OH) 2

СuO + H 2 O = the reaction does not proceed, because possible base containing copper - insoluble

2). Reacts with acids to form salt and water. (Basic oxide and acids react ALWAYS)

K 2 O + 2HCI = 2KCl + H 2 O

CaO + 2HNO 3 = Ca (NO 3) 2 + H 2 O

3). Interaction with acidic oxides to form salt.

Li 2 O + CO 2 = Li 2 CO 3

3MgO + P 2 O 5 = Mg 3 (PO 4) 2

4). Interaction with hydrogen, thus forming metal and water.

CuO + H 2 = Cu + H 2 O

Fe 2 O 3 + 3H 2 = 2Fe + 3H 2 O

II.Acidic oxides.

1). Interaction with water, while acid.(OnlySiO 2 does not interact with water)

CO 2 + H 2 O = H 2 CO 3

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

2). Interaction with soluble bases (alkalis). This produces salt and water.

SO 3 + 2KOH = K 2 SO 4 + H 2 O

N 2 O 5 + 2KOH = 2KNO 3 + H 2 O

3). Interaction with basic oxides. In this case, only salt is formed.

N 2 O 5 + K 2 O = 2KNO 3

Al 2 O 3 + 3SO 3 = Al 2 (SO 4) 3

Basic exercises.

1). Complete the reaction equation. Determine its type.

K 2 O + P 2 O 5 =

Solution.

To write down what is formed as a result, it is necessary to determine what substances entered into the reaction - here it is potassium oxide (basic) and phosphorus oxide (acidic) according to the properties - the result should be SALT (see property No. 3) and the salt consists of atoms metals (in our case, potassium) and an acid residue, which contains phosphorus (i.e., PO 4 -3 - phosphate) Therefore

3K 2 O + R 2 O 5 = 2K 3 PO 4

type of reaction - compound (since two substances react, and one is formed)

2). Carry out transformations (chain).

Ca → CaO → Ca (OH) 2 → CaCO 3 → CaO

Solution

To complete this exercise, you must remember that each arrow is one equation (one chemical reaction). Let's number each arrow. Therefore, it is necessary to write 4 equations. The substance written to the left of the arrow (starting substance) reacts, and the substance written to the right is formed as a result of the reaction (reaction product). Let's decipher the first part of the entry:

Ca +… .. → CaO We draw your attention to the fact that a simple substance enters into a reaction, and an oxide is formed. Knowing the methods of obtaining oxides (No. 1), we come to the conclusion that in this reaction it is necessary to add –oxygen (О 2)

2Са + О 2 → 2СаО

Go to transformation # 2

CaO → Ca (OH) 2

CaO + …… → Ca (OH) 2

We come to the conclusion that here it is necessary to apply the property of basic oxides - interaction with water, since only in this case a base is formed from the oxide.

CaO + H 2 O → Ca (OH) 2

Moving on to transformation # 3

Ca (OH) 2 → CaCO 3

Ca (OH) 2 +… .. = CaCO 3 + …….

We come to the conclusion that here it comes about carbon dioxide CO 2 because only it, when interacting with alkalis, forms a salt (see property No. 2 of acidic oxides)

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

Moving on to transformation # 4

CaCO 3 → CaO

CaCO 3 =… .. CaO + ……

We come to the conclusion that CO 2 is also formed here, since CaCO 3 is an insoluble salt and it is during the decomposition of such substances that oxides are formed.

CaCO 3 = CaO + CO 2

3). Which of the listed substances does CO 2 interact with? Write down the reaction equations.

A). Hydrochloric acid B). Sodium hydroxide B). Potassium oxide d). Water

D). Hydrogen E). Sulfur oxide (IV).

We determine that CO 2 is an acidic oxide. And acid oxides react with water, alkalis and basic oxides ... Therefore, from the given list we choose answers B, C, D And it is with them that we write down the reaction equations:

1). CO 2 + 2NaOH = Na 2 CO 3 + H 2 O

2). CO 2 + K 2 O = K 2 CO 3

Oxides are complex substances consisting of two elements, one of which is oxygen. In the names of oxides, the word oxide is first indicated, then the name of the second element by which it is formed. What are the features of acidic oxides, and how do they differ from other types of oxides?

Classification of oxides

Oxides are divided into salt-forming and non-salt-forming. Already from the name it is clear that non-salt-forming ones do not form salts. There are few such oxides: water H 2 O, oxygen fluoride OF 2 (if it is conventionally considered an oxide), carbon monoxide, or carbon monoxide (II), carbon monoxide CO; nitrogen oxides (I) and (II): N 2 O (dinitrogen oxide, laughing gas) and NO (nitrogen monoxide).

Salt-forming oxides form salts when interacting with acids or alkalis. Bases, amphoteric bases and oxygen-containing acids correspond to them as hydroxides. Accordingly, they are called basic oxides (eg CaO), amphoteric oxides (Al 2 O 3) and acid oxides or acid anhydrides (CO 2).

Rice. 1. Types of oxides.

Often, students are faced with the question of how to distinguish a basic oxide from an acidic one. First of all, you need to pay attention to the second element next to oxygen. Acidic oxides - contain a non-metal or transition metal (CO 2, SO 3, P 2 O 5) basic oxides- contain metal (Na 2 O, FeO, CuO).

Basic properties of acid oxides

Acidic oxides (anhydrides) - substances that exhibit acidic properties and form oxygenated acids. Therefore, acidic oxides correspond to acids. For example, acidic oxides SO 2, SO 3 correspond to the acids H 2 SO 3 and H 2 SO 4.

Rice. 2. Acidic oxides with corresponding acids.

Acidic oxides formed by non-metals and metals with variable valence in the highest degree oxidation (for example, SO 3, Mn 2 O 7), react with basic oxides and alkalis, forming salts:

SO 3 (acidic oxide) + CaO (basic oxide) = CaSO 4 (salt);

Typical reactions are the interaction of acidic oxides with bases resulting in the formation of salt and water:

Mn 2 O 7 (acidic oxide) + 2KOH (alkali) = 2KMnO 4 (salt) + H 2 O (water)

All acidic oxides, except for silicon dioxide SiO 2 (silicic anhydride, silica), react with water, forming acids:

SO 3 (acidic oxide) + H 2 O (water) = H 2 SO 4 (acid)

Acidic oxides are formed by interaction with oxygen of simple and complex substances (S + O 2 = SO 2), or by decomposition as a result of heating complex substances containing oxygen - acids, insoluble bases, salts (H 2 SiO 3 = SiO 2 + H 2 O).

List of acidic oxides:

Acid Oxide Name	Acid Oxide Formula	Acid Oxide Properties
Sulfur (IV) oxide	SO 2	colorless toxic gas with a pungent odor
Sulfur (VI) oxide	SO 3	highly volatile colorless toxic liquid
Carbon monoxide (IV)	CO 2	colorless, odorless gas
Silicon (IV) oxide	SiO 2	colorless crystals with strength
Phosphorus (V) oxide	P 2 O 5	white, highly flammable powder with an unpleasant odor
Nitric oxide (V)	N 2 O 5	substance composed of colorless volatile crystals
Chlorine (VII) oxide	Cl 2 O 7	colorless oily toxic liquid
Manganese (VII) oxide	Mn 2 O 7	liquid with a metallic luster, which is a strong oxidizing agent.

Today we begin our acquaintance with the most important classes not organic compounds... Inorganic substances are divided according to their composition, as you already know, into simple and complex ones.

OXIDE	ACID	BASE	SALT
E x O y	NnA A - acid residue	Me (OH)b OH - hydroxyl group	Me n A b

Complex inorganic substances are divided into four classes: oxides, acids, bases, salts. We start with the oxide class.

OXIDES

Oxides are complex substances consisting of two chemical elements, one of which is oxygen, with valency equal to 2. Only one chemical element - fluorine, combining with oxygen, forms not an oxide, but oxygen fluoride OF 2.
They are called simply - "oxide + element name" (see table). If the valence of a chemical element is variable, then it is indicated by a Roman numeral enclosed in parentheses after the name of the chemical element.

Formula	Name	Formula	Name
	carbon monoxide (II)	Fe 2 O 3	iron (III) oxide
	nitric oxide (II)	CrO 3	chromium (VI) oxide
Al 2 O 3	aluminium oxide		zinc oxide
N 2 O 5	nitric oxide (V)	Mn 2 O 7	manganese (VII) oxide

Classification of oxides

All oxides can be divided into two groups: salt-forming (basic, acidic, amphoteric) and non-salt-forming or indifferent.

Metal oxides Me x O y			Nonmetal oxides notMe x O y
The main	Acidic	Amphoteric	Acidic	Indifferent
I, II Me	V-VII Me	ZnO, BeO, Al 2 O 3, Fe 2 O 3, Cr 2 O 3	> II not me	I, II not me CO, NO, N 2 O

1). Basic oxides Are the oxides to which the bases correspond. Basic oxides include oxides metals 1 and 2 groups, as well metals side subgroups with valence I and II (except for ZnO - zinc oxide and BeO - beryllium oxide):

2). Acidic oxides Are oxides to which acids correspond. Acid oxides include nonmetal oxides (except for non-salt-forming - indifferent), as well as metal oxides side subgroups with a valency of V before Vii (For example, CrO 3 is chromium (VI) oxide, Mn 2 O 7 is manganese (VII) oxide):

3). Amphoteric oxides- these are oxides, which correspond to bases and acids. These include metal oxides major and minor subgroups with valence III , sometimes IV , as well as zinc and beryllium (For example, BeO, ZnO, Al 2 O 3, Cr 2 O 3).

4). Non-salt-forming oxides- these are oxides indifferent to acids and bases. These include nonmetal oxides with valence I and II (For example, N 2 O, NO, CO).

Conclusion: the nature of the properties of oxides primarily depends on the valence of the element.

For example, chromium oxides:

CrO (II- main);

Cr 2 O 3 (III- amphoteric);

CrO 3 (Vii- acidic).

Classification of oxides

(by solubility in water)

Acidic oxides	Basic oxides	Amphoteric oxides
Soluble in water. Exception - SiO 2 (insoluble in water)	Only oxides of alkali and alkaline earth metals dissolve in water (these are metals I "A" and II "A" groups, excluding Be, Mg)	They do not interact with water. Insoluble in water

Complete tasks:

1. Write down separately chemical formulas salt-forming acid and basic oxides.

NaOH, AlCl 3, K 2 O, H 2 SO 4, SO 3, P 2 O 5, HNO 3, CaO, CO.

2. Given substances : CaO, NaOH, CO 2, H 2 SO 3, CaCl 2, FeCl 3, Zn (OH) 2, N 2 O 5, Al 2 O 3, Ca (OH) 2, CO 2, N 2 O, FeO, SO 3, Na 2 SO 4, ZnO, CaCO 3, Mn 2 O 7, CuO, KOH, CO, Fe (OH) 3

Write down oxides and classify them.

Obtaining oxides

Simulator "Interaction of oxygen with simple substances"

1. Combustion of substances (Oxidation with oxygen)	a) simple substances Training apparatus	2Mg + O 2 = 2MgO
	b) complex substances	2H 2 S + 3O 2 = 2H 2 O + 2SO 2
2.Decomposition of complex substances (use acid table, see appendices)	a) salts SALTt= BASIC OXIDE + ACID OXIDE	СaCO 3 = CaO + CO 2
	b) Insoluble bases Me (OH)bt= Me x O y+ H 2 O	Cu (OH) 2 t = CuO + H 2 O
	c) oxygenated acids NnA =ACID OXIDE + H 2 O	H 2 SO 3 = H 2 O + SO 2

Physical properties of oxides

At room temperature most oxides are solids (CaO, Fe 2 O 3, etc.), some are liquids (H 2 O, Cl 2 O 7, etc.) and gases (NO, SO 2, etc.).

Chemical properties of oxides

CHEMICAL PROPERTIES OF BASIC OXIDES 1. Basic oxide + Acidic oxide = Salt (p. Compound) CaO + SO 2 = CaSO 3 2. Basic oxide + Acid = Salt + H 2 O (p. Exchange) 3 K 2 O + 2 H 3 PO 4 = 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Water = Alkali (p. Compound) Na 2 O + H 2 O = 2 NaOH

CHEMICAL PROPERTIES OF ACID OXIDES 1. Acid oxide + Water = Acid (p. Compound) C O 2 + H 2 O = H 2 CO 3, SiO 2 - does not react 2. Acid oxide + Base = Salt + H 2 O (p. Exchange) P 2 O 5 + 6 KOH = 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Acidic oxide = Salt (p. Compound) CaO + SO 2 = CaSO 3 4. The less volatile displace the more volatile ones from their salts CaCO 3 + SiO 2 = CaSiO 3 + CO 2

CHEMICAL PROPERTIES OF AMPHOTHERIC OXIDES They interact with both acids and alkalis. ZnO + 2 HCl = ZnCl 2 + H 2 O ZnO + 2 NaOH + H 2 O = Na 2 [Zn (OH) 4] (in solution) ZnO + 2 NaOH = Na 2 ZnO 2 + H 2 O (when fusion)

Application of oxides

Some oxides do not dissolve in water, but many enter into a compound reaction with water:

SO 3 + H 2 O = H 2 SO 4

CaO + H 2 O = Ca( OH) 2

The result is often highly desirable and useful compounds. For example, H 2 SO 4 is sulfuric acid, Ca (OH) 2 is slaked lime, etc.

If oxides are insoluble in water, then people skillfully use this property as well. For example, zinc oxide ZnO is a white substance, therefore it is used to prepare white oil paint (zinc white). Since ZnO is practically insoluble in water, zinc white can be used to paint any surfaces, including those that are exposed to atmospheric precipitation. Insolubility and non-toxicity make it possible to use this oxide in the manufacture of cosmetic creams and powders. Pharmacists make it an astringent and drying powder for external use.

Titanium (IV) oxide - TiO 2 possesses the same valuable properties. He also has a handsome White color and is used for the manufacture of titanium white. TiO 2 does not dissolve not only in water, but also in acids; therefore, coatings made of this oxide are especially resistant. This oxide is added to the plastic to give it a white color. It is part of enamels for metal and ceramic dishes.

Chromium (III) oxide - Cr 2 O 3 - very strong crystals of dark green color, insoluble in water. Cr 2 O 3 is used as a pigment (paint) in the manufacture of decorative green glass and ceramics. The GOI paste known to many (abbreviated from the name "State Optical Institute") is used for grinding and polishing optics, metal products, in jewelry.

Due to the insolubility and strength of chromium (III) oxide, it is also used in printing inks (for example, for painting banknotes). In general, oxides of many metals are used as pigments for a wide variety of paints, although this is far from their only application.

Tasks for consolidation

1. Write down separately the chemical formulas of salt-forming acid and basic oxides.

NaOH, AlCl 3, K 2 O, H 2 SO 4, SO 3, P 2 O 5, HNO 3, CaO, CO.

2. Given substances : CaO, NaOH, CO 2, H 2 SO 3, CaCl 2, FeCl 3, Zn (OH) 2, N 2 O 5, Al 2 O 3, Ca (OH) 2, CO 2, N 2 O, FeO, SO 3, Na 2 SO 4, ZnO, CaCO 3, Mn 2 O 7, CuO, KOH, CO, Fe (OH) 3

Choose from the list: basic oxides, acidic oxides, indifferent oxides, amphoteric oxides and give them names.

3. Finish CCM, indicate the type of reaction, name the reaction products

Na 2 O + H 2 O =

N 2 O 5 + H 2 O =

CaO + HNO 3 =

NaOH + P 2 O 5 =

K 2 O + CO 2 =

Cu (OH) 2 =? +?

4. Carry out the transformations according to the scheme:

1) K → K 2 O → KOH → K 2 SO 4

2) S → SO 2 → H 2 SO 3 → Na 2 SO 3

3) P → P 2 O 5 → H 3 PO 4 → K 3 PO 4

If you were not fond of chemistry at school, you are unlikely to immediately remember what oxides are and what their role in environment... It is actually a fairly common type of compound and is most commonly found in the environment in the form of water, rust, carbon dioxide, and sand. Also, oxides include minerals - type rocks having a crystalline structure.

Definition

Oxides are chemical compounds, the formula of which contains at least one oxygen atom and atoms of other chemical elements. Metal oxides generally contain oxygen anions in the -2 oxidation state. significant portion Earth crust consists of solid oxides that arose during the oxidation of elements with oxygen from air or water. When a hydrocarbon is burned, two main carbon oxides are formed: carbon monoxide (carbon monoxide, CO) and carbon dioxide (carbon dioxide, CO 2).

Classification of oxides

All oxides are usually divided into two large groups:

• salt-forming oxides;
• non-salt-forming oxides.

Salt-forming oxides - chemical substances, which, in addition to oxygen, contain elements of metals and non-metals, which form acids when in contact with water, and when combined with bases - salts.

Salt-forming oxides, in turn, are subdivided into:

• basic oxides, in which, upon oxidation, the second element (1, 2 and sometimes a 3-valent metal) becomes a cation (Li 2 O, Na 2 O, K 2 O, CuO, Ag 2 O, MgO, CaO, SrO, BaO, HgO , MnO, CrO, NiO, Fr 2 O, Cs 2 O, Rb 2 O, FeO);
• acid oxides, in which, during the formation of a salt, the second element is attached to a negatively charged oxygen atom (CO 2, SO 2, SO 3, SiO 2, P 2 O 5, CrO 3, Mn 2 O 7, NO 2, Cl 2 O 5, Cl 2 O 3);
• amphoteric oxides, in which the second element (3 and 4-valence metals or exceptions such as zinc oxide, beryllium oxide, tin oxide and lead oxide) can become both a cation and add to an anion (ZnO, Cr 2 O 3, Al 2 O 3, SnO, SnO 2, PbO, PbO 2, TiO 2, MnO 2, Fe 2 O 3, BeO).

Non-salt-forming oxides exhibit neither acidic, nor basic, nor amphoteric properties and, as the name suggests, do not form salts (CO, NO, NO 2, (FeFe 2) O 4).

Properties of oxides

1. Oxygen atoms in oxides are highly reactive. Due to the fact that the oxygen atom is always negatively charged, it forms stable chemical bonds with almost all elements, which leads to a wide variety of oxides.
2. Noble metals such as gold and platinum are prized because they do not oxidize naturally... Corrosion of metals occurs as a result of hydrolysis or oxidation with oxygen. The combination of water and oxygen only speeds up the reaction rate.
3. In the presence of water and oxygen (or just air), the oxidation reaction of some elements, for example, sodium, occurs rapidly and can be dangerous to humans.
4. Oxides create a protective oxide film on the surface. An example is aluminum foil, which corrodes at a much slower rate due to its thin alumina coating.
5. Most metal oxides have a polymer structure, so they are not destroyed by solvents.
6. Oxides dissolve under the action of acids and bases. Oxides that can react with both acids and bases are called amphoteric. Metals tend to form basic oxides, non-metals form acidic oxides, and amphoteric oxides are derived from alkali metals (metalloids).
7. The amount of metal oxide can be reduced by the action of certain organic compounds. These redox reactions underlie many important chemical transformations, such as the detoxification of drugs by the P450 enzymes and the production of ethylene oxide, which is then used to produce antifreeze.

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