Toxic elements (in particular, some heavy metals) constitute an extensive and very dangerous group of substances in toxicological terms. Usually 14 elements are considered: Hg (mercury), Pb (lead), Cd (cadmium), As (arsenic), Sb (antimony), Sn (tin), Zn (zinc), Al (aluminum), Be (beryllium), Fe (iron), Cu (copper), Ba (barium), Cr (chromium), Tl (thallium). Of course, not all of the listed elements are poisonous, some of them are necessary for the normal life of humans and animals. Therefore, it is often difficult to draw a clear line between substances that are biologically necessary and harmful to human health.
In most cases, the realization of one effect or another depends on the concentration. With an increase in the optimal physiological concentration of an element in the body, intoxication, and the deficiency of many elements in food and water can lead to quite severe and difficult to recognize deficiency phenomena.
Dependence of harmful or useful action of some elements on concentration is shown in fig. 11.3.
For substances belonging to the so-called supertoxicants, there is no plateau characterizing the norm (or a very short one), and the steepness of the descending branch characterizes the toxicity of the substance (Fig. 11.4).
Pollution of water bodies, atmosphere, soil, agricultural plants and food products with toxic metals occurs due to:
Emissions from industrial enterprises (especially coal, metallurgical and chemical industries);
Urban transport emissions (referring to lead pollution from combustion leaded gasoline);
Applications in the canning industry of low-quality internal coatings and in violation of the technology of solders;
Contact with equipment (a very limited number of steels and other alloys are allowed for food purposes).
For most products, maximum allowable concentrations (MPCs) of toxic elements have been established; more stringent requirements are imposed on children's and dietary products.
The most dangerous of the above elements are mercury (Hg), lead (Pb), cadmium (Cd).
- one of the most dangerous and highly toxic elements, which has the ability to accumulate in plants and in the body of animals and humans, that is, it is a poison of cumulative action.
The toxicity of mercury depends on the type of its compounds, which are absorbed, metabolized and excreted from the body in different ways. The most toxic short-chain alkylmercury compounds are methylmercury, ethylmercury, and dimethylmercury. The mechanism of the toxic action of mercury is associated with its interaction with sulfhydryl groups of proteins. By blocking them, mercury changes the properties or inactivates a number of vital enzymes. Inorganic mercury compounds disrupt the metabolism of ascorbic acid, pyridoxine, calcium, copper, zinc, selenium; organic - metabolism of proteins, cysteine, ascorbic acid, tocopherols, iron, copper, manganese, selenium.
Mercury has a protective effect on the human body zinc and especially, selenium. It is assumed that the protective effect of selenium is due to the demethylation of mercury and the formation of a non-toxic compound - the selenium-mercury complex.
The high toxicity of mercury is also evidenced by very low MPC values: 0.0003 mg/m 3 in air and 0.0005 mg/l in water. A safe level of mercury in the blood is 50-100 µg/L. A person receives about 0.05 mg of mercury with a daily diet, which is in line with the FAO/WHO recommendations.
Mercury enters the human body to the greatest extent with fish products, in which its content can many times exceed the MPC. Fish meat is distinguished by the highest concentration of mercury and its compounds, since it actively accumulates them from water and feed, which includes various aquatic organisms rich in mercury. For example, predatory freshwater fish can contain 107 to 509 µg/kg, non-predatory freshwater fish 78 to 200 µg/kg, and oceanic non-predatory fish 300 to 600 µg/kg Hg.
The body of fish is able to synthesize methyl mercury, which accumulates in the liver. In some fish species, muscles contain a protein - metallothionein, which forms complex compounds with various metals, including mercury, thereby contributing to the accumulation of mercury in the body and its transfer through food chains. In these fish, the mercury content reaches very high concentrations: saberfish contains from 500 to 20,000 µg/kg, and Pacific marlin from 5000 to 14,000 µg/kg. Other products are characterized by the following mercury content (mcg/kg).
In animal products: meat 6-20, liver 20-35, kidneys 20-70, milk 2-12, butter 2-5, eggs 2-15; in edible parts of agricultural plants: vegetables 3-59, fruits 10-124, legumes 8-16, cereals 10-103; in cap mushrooms 6-447, in overripe mushrooms up to 2000 mcg/kg, and unlike plants, methylmercury can be synthesized in mushrooms. When cooking fish and meat, the concentration of mercury in them decreases, while similar processing of mushrooms remains unchanged. This difference is explained by the fact that in mushrooms mercury is associated with amino groups of nitrogen-containing compounds, in fish and meat - with sulfur-containing amino acids.
Lead - one of the most widespread and dangerous toxicants. The history of its use is very ancient, which is due to the relative simplicity of its production and its high prevalence in the earth's crust (1.6x10 -3%). Lead compounds - Pb 3 O 4 and PbSO 4 - are the basis of widely used pigments: red lead and white lead. Glazes that are used to coat pottery also contain Pb compounds.
Metallic lead has been used in the construction of water pipes since the times of Ancient Rome. At present, the list of areas of its application is very wide: the production of batteries, electric cables, chemical engineering, the nuclear industry, the production of enamels, putties, varnishes, crystal, pyrotechnic products, matches, plastics, etc.
World production of lead is more than 3.5 x 10 6 tons per year. As a result of human production activities, 500-600 thousand tons annually fall into natural waters, and about 450 thousand tons are emitted into the atmosphere in a processed and finely dispersed state, the vast majority of which settles on the Earth's surface. The main sources of air pollution with lead are vehicle exhaust gases (260,000 tons) and coal combustion (about 30,000 tons).
In countries where the use of gasoline with added tetraethyl lead reduced to a minimum, the lead content in the air has been reduced many times over. It should be emphasized that many plants accumulate lead, which is transmitted through food chains and is found in the meat and milk of farm animals, especially active accumulation of lead occurs near industrial centers and major highways.
The daily intake of lead in the human body with food is 0.1-0.5 mg, with water - 0.02 mg. The content of lead (in mg/kg) in various products is as follows: fruits 0.01-0.6; vegetables 0.02-1.6; cereals 0.03-3.0; bakery products 0.03-0.82; meat and fish 0.01-0.78; milk 0.01-0.1. In the human body, an average of 10% of incoming lead is absorbed, in children - 30-40%. From the blood, lead enters the soft tissues and bones, where it is deposited in the form of triphosphate.
The mechanism of the toxic action of lead has a dual focus. Firstly, the blockade of the functional SH-groups of proteins and, as a result, the inactivation of enzymes, and secondly, the penetration of lead into nerve and muscle cells, the formation of lead lactate, then lead phosphate, which create a cellular barrier for the penetration of Ca 2+ ions. The main targets of lead exposure are the hematopoietic, nervous and digestive systems, as well as the kidneys.
Lead intoxication can lead to serious health problems, manifested in frequent headaches, dizziness, increased fatigue, irritability, poor sleep, muscle hypotension, and in the most severe cases to paralysis and paresis, mental retardation. Malnutrition, deficiency in the diet of calcium, phosphorus, iron, pectins, proteins (or increased intake of calciferol) increase the absorption of lead, and hence its toxicity. The allowable daily intake (ADD) of lead is 0.007 mg/kg; MPC value in drinking water is 0.05 mg/l.
Measures to prevent lead contamination of raw materials and food products should include state and departmental control over industrial emissions of lead into the atmosphere, water bodies and soil. It is necessary to significantly reduce or completely eliminate the use of tetraethyl lead in gasoline, lead stabilizers, PVC products, dyes, packaging materials, etc.
Cadmium widely used in various industries. Cadmium enters the air together with lead when fuel is burned at thermal power plants, with gas emissions from enterprises that produce or use cadmium. Soil contamination with cadmium occurs when aerosol cadmium settles from the air and is supplemented by the application of mineral fertilizers: superphosphate (7.2 mg/kg), potassium phosphate (4.7 mg/kg), saltpeter (0.7 mg/kg).
The content of cadmium is also noticeable in manure, where it is found as a result of the following chain of transitions: air - soil - plants - herbivores - manure. In some countries, cadmium salts are used as antiseptic and anthelmintic drugs in veterinary medicine. All this determines the main ways of cadmium pollution of the environment, and, consequently, of food raw materials and foodstuffs.
The content of cadmium (in mcg/kg) in various products is as follows. Plant foods: cereals 28-95, peas 15-19, beans 5-12, potatoes 12-50, cabbage 2-26, tomatoes 10-30, lettuce 17-23, fruit 9-42, vegetable oil 10-50, sugar 5-31, mushrooms 100-500; in livestock products: milk - 2.4, cottage cheese - 6.0, eggs 23-250. It has been established that approximately 80% of cadmium enters the human body with food, 20% - through the lungs from the atmosphere and when smoking. With the diet, an adult receives up to 150 mcg / kg and more of cadmium per day.
One cigarette contains 1.5-2.0 µg of Cd. Like mercury and lead, cadmium is not a vital metal. Once in the body, cadmium exhibits a strong toxic effect, the main target of which is the kidneys. The mechanism of the toxic action of cadmium is associated with the blockade of sulfhydryl groups of proteins; in addition, it is an antagonist of zinc, cobalt, selenium, inhibits the activity of enzymes containing these metals. The ability of cadmium to disrupt the exchange of iron and calcium is known.
All this can lead to a wide range of diseases: hypertension, anemia, coronary heart disease, kidney failure and others. Marked carcinogenic, mutagenic and teratogenic effects of cadmium. According to WHO recommendations, the acceptable daily intake (ADD) of cadmium is 1 µg/kg of body weight.
Of great importance in the prevention of cadmium intoxication is proper nutrition (inclusion in the diet of proteins rich in sulfur-containing amino acids, ascorbic acid, iron, zinc, selenium, calcium), control of cadmium content (polarographic, atomic absorption analyzes) and exclusion from the diet of foods rich in cadmium.
aluminum. The first data on the toxicity of aluminum were obtained in the 70s. XX century, and this was a surprise for mankind. Being the third most common element of the earth's crust (8.8% of the mass of the earth's crust is A1) and having valuable qualities, metallic aluminum has found wide application in technology and everyday life. Suppliers of aluminum to the human body are aluminum dishes, if they come into contact with an acidic or alkaline environment, water, which is enriched with A1 3+ ions when treated with aluminum sulfate at water treatment plants.
Acid rain also plays a significant role in environmental pollution with Al 3+ ions. Do not abuse drugs containing aluminum hydroxide: antihemorrhoidal, antiarthritic, lowering the acidity of gastric juice. As a buffer additive, aluminum hydroxide is introduced into some aspirin preparations and into lipstick. Among food products, tea has the highest concentration of aluminum (up to 20 mg/g).
A1 3+ ions entering the human body in the form of insoluble phosphate are excreted with feces, partially absorbed into the blood and excreted by the kidneys. When kidney function is impaired, aluminum accumulates, which leads to impaired metabolism Ca, Mg, P, F, accompanied by an increase in bone fragility, the development of various forms of anemia. In addition, more formidable manifestations of aluminum toxicity were found: speech impairment, memory lapses, impaired orientation, etc. All this makes it possible to bring the "harmless" aluminum, which until recently was considered non-toxic, to the "dark trio" of supertoxicants: Hg, Pb , CD.
Arsenic as an element in its pure form, it is poisonous only in high concentrations. It belongs to those trace elements, the need for which for the life of the human body has not been proven, and its compounds, such as arsenic anhydride, arsenites and arsenates, are highly toxic. Arsenic is found in all objects of the biosphere (in the earth's crust - 2 mg / kg, in sea water - 5 μg / kg). Known sources of environmental pollution with arsenic are power plants using brown coal, copper smelters; it is used in the production of semiconductors, glass, dyes, insecticides, fungicides, etc.
The normal level of arsenic in foodstuffs should not exceed 1 mg/kg. So, for example, the background content of arsenic (mg/kg): in vegetables and fruits 0.01-0.2; in cereals 0.006-1.2; in beef 0.005-0.05; in the liver 2.0; eggs 0.003-0.03; in cow's milk 0.005-0.01. An increased content of arsenic is noted in fish and other aquatic organisms, in particular, in crustaceans and molluscs. According to the FAO / WHO, an average of 0.05-0.45 mg of arsenic enters the human body with a daily diet. DSD - 0.05 mg / kg body weight.
Depending on the dose, arsenic can cause acute and chronic poisoning, a single dose of 30 mg of arsenic is fatal to humans. The mechanism of the toxic action of arsenic is associated with the blocking of SH-groups of proteins and enzymes that perform a wide variety of functions in the body.
A1. The particle has the electronic configuration of the argon atom:
A2. In the series of chemical elements Na→Mg→Al→Si
1) the number of valence electrons in atoms increases
2) the number of electron layers in atoms decreases
3) the number of protons in the nuclei of atoms decreases
4) the radii of atoms increase
A3. Are the following statements about metals correct?
A. Group IIA metals form higher oxides of composition R 2 O.
B. Metallic properties increase in the series Na→K→Rb.
1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong
A4. Due to the common electron pair, a chemical bond is formed in the compound
A5. The oxidation state of oxygen in the BaO 2 compound is
A6. The molecular crystal lattice has
1) quicklime
2) dimethyl ether
4) pyrolusite
A7. Among the listed substances:
oxides are:
1) VGE 2) ABC 3) ABE 4) WHERE
A8. Are the following statements about the chemical properties of chlorine correct?
A. Many dyes become colorless in chlorine water.
B. Chlorine can interact with potassium bromide.
1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong
A9. Alkali is formed when dissolved in water.
1) chlorine oxide (I)
2) chromium oxide (VI)
3) barium oxide
4) magnesium oxide
A10. Hydrogen is not released in the reaction of zinc with
1) nitric acid
2) sodium hydroxide
3) hydrochloric acid
4) sulfuric acid
A11. Calcium bicarbonate is formed from calcium carbonate by the action of
1) excess hydrochloric acid
2) aqueous solution of KHCO 3
3) an aqueous solution of CO 2
4) hydrogen
A12. In the NaNaH transformation scheme 
NaOH
Substances X 1 and X 2 are respectively
A13. Only ϭ-bonds are present in the molecule
1) propionic acid
2) ethylene
4) cyclobutane
A14. Both hexane and toluene react with
1) bromine water
2) potassium permanganate solution
4) hydrogen
A15. Ethylene glycol interacts with
2) nitric acid
3) iron oxide (II)
A16. As an aldehyde and as an alcohol, glucose interacts with a substance whose formula
A17. Aldehydes can be obtained from
1) hydration of alkenes
2) dehydration of alcohols
3) hydrohalogenation of alkynes
4) oxidation of primary alcohols
A18. In the transformation scheme
CH 3 CHO → X → C 2 H 4
substance X is
4) CH 3 CH 2 Cl
A19. During the dehydration reaction,
1) splitting off water
2) water connection
3) addition of hydrogen
4) elimination of hydrogen
A20. For the speed of the reaction
CaCO 3 + 2HCl (p-p) = CaCl 2 + H 2 O + CO 2
does not affect the change
1) pressure
2) temperature
3) concentration of hydrochloric acid
4) surface area of contact of substances
A21. On the shift of chemical equilibrium in the system 2HBr (g) ⇄ H 2 (g) + Br 2 (g) –Q
does not affect the change
1) pressure
2) temperature
3) hydrogen concentration
4) concentration of hydrogen bromide
A22. A weak electrolyte is a substance whose formula is
A23. A precipitate precipitates when the solutions react
1) potassium hydroxide and sulfurous acid
2) sodium sulfite and nitric acid
3) sodium bromide and iron (II) nitrate
4) chromium (III) chloride and lithium hydroxide
A24. For the human body, each of the two ions is the most toxic
3) Pb 2+ and Hg 2+
4) Ca 2+ and Hg 2+
A25. Are the following statements about natural gas correct?
A. The main constituents of natural gas are ethane and its homologues.
B. Natural gas serves as a raw material for the production of acetylene.
1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong
A26. The mass of water that must be added to 200 g of a solution of potassium nitrate with a mass fraction of 30% so that the mass fraction of salt in the solution becomes 10%
A27. As a result of the reaction, the thermochemical equation of which
2SO 2 (g) + O 2 (g) \u003d 2SO 3 (g) + 198 kJ,
297 kJ of heat was released. The volume of sulfur oxide (IV) consumed is equal to
28. The volume of carbon dioxide (n.o.) obtained by the interaction of 5.3 g of sodium carbonate with an excess of hydrochloric acid solution is
2013, the USE in English begins. I read the first task and do not understand what I want more - to laugh or to be indignant. The phrase “Kate is thinking about a present for her former school friend” I saw two days ago in the material “Snob” about the mass drain of exam assignments. On the Internet, identical real tasks hung for at least three days. In Russian - a few hours, in literature - about a week. As a result, 10 thousand 100-point students were counted in the country (according to data from the official USE portal), in 2012 there were 3571 people.
Happy schoolchildren achieved high results in top universities. On average, previously seen tests raised the applicant's result by twenty points. Educational institutions like Moscow State University tried to fight back with the help of additional exams. But this did not help much either, because enrollment is based on the sum of all tests.
It cannot be said that last year's leaks led to the fact that only illiterate people entered universities. In order to write off correctly, intelligence is also required, and universities had the opportunity to restore justice at the very first session. But faith in the state's ability to fight corruption has been undermined.
USE on garlic
What about this year? Rosobrnadzor swears that the plums have been defeated. Indeed, not a single message on the topic “Answers have been posted on the Internet again”, but as many as you like “In region N, they were kicked out for cheating.” The first reaction in the best traditions of Stanislavsky: “I don’t believe.” I am writing to my acquaintances: “Was there a drain?” Eleventh graders from different parts of the country swear in unison that nothing happened:
- As far as I know, no one has found the correct KIMs or answers, from my acquaintances for sure. Although there were spurs, - graduate Alena admits.
I still don't believe it. I am looking for assignments. After five minutes of searching for VKontakte, the following dialogue begins:
- Timur, hello! Interested in the answers to the exam (reserve dates) in Russian and mathematics. What is the price of the issue and how to transfer the money? Very, very necessary!
- Three hundred rubles answers + KIMS. One item. The total will be 600 rubles for two items ...
There are many such ads, no one removes them. The only thing that bothers me is the price. Last year, in some cases, tens of thousands were asked. I'm starting to trust officials.
- There was definitely no such thing as in 2013. I work with schoolchildren, information from them. Two months before the exam, people began to appear around the schools, telling the children: “You are now giving us 1,500 rubles, we will answer the day before the exam.” The classes were dropped. But no one seemed to get the right answers. How could they track the Internet, do not give tasks to the children of their friends. This cannot be proven, but there is a small group of schoolchildren who have to write only their name on the form - and they will be given the necessary points. I think all the machinations came down to this, - Irina Maslyakova, Senior Lecturer, Department of Higher Mathematics, Russian University of Economics. Plekhanov, confirms my opinion.
— This year the control was much more serious. There were fewer people interested in high scores: the results of the Unified State Examination were excluded from the indicators of the work of governors. They didn’t catch everyone, but they showed by examples that it’s impossible to do this with impunity,” adds Yuri Romanov, senior lecturer at the History Department of the Moscow State Pedagogical University.
When it wants, our state knows how to work and stop violations. Everything was foreseen, everything worked as it should, admission to universities this summer will be fair. But here, in the depths of consciousness, the opposite “I don’t believe” arose again.
Echoes of last year
“Admission to organizations that carry out educational activities in undergraduate and specialist programs is allowed based on the results of the Unified State Examination issued in 2012 and 2013 and valid until the end of 2016 and 2017, respectively” - a document with this text appeared on the Rosobrnadzor website.
Exam results are now valid for four years. That is, it turns out that the student who cheated last year will still be able to enter a more prestigious university this year. Current 11th graders will have lower scores.
- This was announced by the Minister of Education himself. What to do with it, they do not know. So far, the requirements have simply been reduced. There were so many twos in Russian that I had to greatly reduce the passing score, - comments Irina Maslyakova.
That is, the Unified State Exam was held relatively honestly, but the effect of last year will be felt for several more years. I really want to believe that over time, security measures will give results. Pupils, however, it is a pity. They will have to finally get used to psychological pressure, searches at the entrance to the office and video cameras around.
Could you pass the exam?
Variants from the demo version of FIPI for 2014 are given (the simplest tasks are selected)
Russian language
In which row in all words is the same letter missing?
- By ... masonry, about ... fighting, on ... lowercase.
- Pr ... stand up, pr ... glue, pr ... school.
- On ... to play, over ... investments, from ... say.
- Bar ... erny, with ... sting, monkey ... yana.
Biology
The gender of the unborn child is formed when:
- fusion of gametes;
- maturation of gametes;
- crushing of blastomeres;
- organ formation.
Geography
Which of the following countries has the largest proportion of people over 65 in the age structure of the population?
- Brazil.
- Algeria.
- Bangladesh.
- Norway.
Mathematics
There are only 25 tickets in the collection of biology tickets, in two of them there is a question about mushrooms. At the exam, the student gets one randomly selected ticket from this collection. Find
the probability that this ticket will not contain a question about mushrooms.
Story
Which of the following can be attributed to the results of the industrialization of the USSR in the pre-war period?
- Creation of a complex of heavy industry enterprises.
- Reducing military spending.
- Intensive development of light industry.
- Formation of a mixed economy.
Physics
Gas particles are on average at such distances from each other at which the forces of attraction between them are negligible. This explains:
- high speed of gas particles;
- the value of the speed of sound in gas;
- propagation of sound waves in gas;
- the ability of gases to expand indefinitely.
Chemistry
For the human body, each of the two ions is the most toxic:
- K+ and Pb2+
- Na+ and Cu2+
- Cu2+ and Hg2+
- Ca2+ and Hg2+
Right answers
Russian language - 2, biology - 1, geography - 4, mathematics - 0.92, history - 1, physics - 4, chemistry - 3.
Preview:
Test No. 1
The structure of matter
1 option | Option 2 |
SiO 2 , K 3 N, O 2 , C 4 H 10 . 2) Give a description of the substance whose formula CH 2 \u003d C (CH 3) - C (CH 3) \u003d CH 2 according to the plan: A) name, class; C) types of isomerism; CaCO 3 → CaO → Ca (OH) 2 → Ca (NO 3) 2 → CaSiO 3 Name the reaction products. 4) Zinc was added to a solution of hydrochloric acid with a volume of 120 ml with a mass fraction of 15%, a density of 1.07 g/ml. Determine the volume of hydrogen (n.o.) that will be released as a result of the reaction. | 1) Determine the type of chemical bond in substances whose formulas are: N 2 , PH 3 , Na 2 O, C 2 H 4 . Write their structural formulas. 2) Give a description of the substance whose formula is CH≡C−C(CH 3) 2 −CH 3 according to the plan: A) name, class; B) hybridization of all carbon atoms; C) types of isomerism; D) make 1 isomer and 1 homologue and give them a name. 3) Write the reaction equations with which you can carry out the following transformations: СuO→Cu→CuCl 2 →Cu(OH) 2 →CuSO 4 Name the reaction products. 4) Calculate the volume of ammonia, measured at N.C., which will be required to completely neutralize a 20 ml sulfuric acid solution with a mass fraction of 3%, a density of 1.02 g/ml. |
Preview:
Test No. 2
chemical reactions
1 option
PART A | PART B & C |
A 1. Specify the correct characteristics of the reaction C + O 2 \u003d CO 2 + Q a) connection, OVR, exothermic, reversible; b) exchange, OVR is not, irreversible, endothermic; c) compound, OVR, exothermic, irreversible; d) compound, OVR is not, endothermic, irreversible. A 2. Specify the hydrogenation reaction: a) interaction of ethene with water; b) synthesis of propane from propene; c) synthesis of ethene from ethanol; d) synthesis of polyethylene. A 3. The reaction taking place at the phase boundary: A 4. From an increase in the surface area of contact of substances does not depend reaction speed between: a) S and Al; b) H 2 and Cl 2; c) Al and Cl 2 ; d) Mg and HCl. A 5. Equilibrium in the CaCO reaction 3 ↔ CaO + CO 2 – Q shifts to the right at: a) ↓t, p; b) t, ↓p; c) t, p; d) ↓t, ↓p. A 6. The reaction whose equation is S + 6HNO 3 \u003d H 2 SO 4 + 6NO 2 + 2H 2 O corresponds to the scheme of changing the degree of nitrogen oxidation a) N +4 → N +5; b) N +5 → N +4; c) N 0 → N +4; d) N +3 → N -3. A 7. Only hydroxide ions as anions are formed during dissociation: A) MgOHCl; b) NaOH; c) HONO 2; d) HCOOH. A 8. Dissociation in three steps is possible in solution: a) aluminum chloride; b) potassium orthophosphate; c) aluminum nitrate; d) phosphoric acid. A 9. Abbreviated ionic reaction equation Ba 2+ + SO 4 2- = BaSO 4 a) Ba + H 2 SO 4; b) BaO + HCl; c) BaO + H 2 SO 4; d) BaCl 2 + H 2 SO 4; A 10. The acid reaction of the medium has a solution: a) Na 2 SO 4; b) CaCO 3 ; c) AlCl 3 ; d) NaCl. | IN 1. In the above scheme, HNO 3 + P + H 2 O → NO + H 3 PO 4 IN 2. a) aluminum sulfate; 1) does not undergo hydrolysis; b) potassium sulfite; 2) hydrolysis by cation; c) sodium phenolate; 3) anion hydrolysis; d) barium nitrate. 4) hydrolysis by cation and anion From 1. In 300 ml of a solution of hydrochloric acid with a density of 1.05 g / ml with a mass fraction of 10%, iron was dissolved with a mass of 11.2 g. Calculate the mass fraction of iron chloride (2) in the resulting solution. |
Test No. 2
chemical reactions
Option 2
PART A | PART B & C |
A 1. Specify the correct characteristics of the reaction 2H 2 O↔ 2H 2 + O 2 -Q a) connection, OVR, endothermic, reversible; b) decomposition, OVR, endothermic, reversible; c) decomposition, OVR, exothermic, reversible; d) decomposition, OVR is not, endothermic, irreversible. A 2. Specify the reaction of dehydration: a) interaction of ethene with water; b) obtaining butene-2 from butanol-2; c) ammonia synthesis; d) protein hydrolysis. A 3. The reaction taking place in a homogeneous medium: a) catalytic; b) homogeneous; c) heterogeneous; d) OVR. A 4. To increase the rate of a chemical reaction Zn + 2H + = Zn 2+ + H 2 + Q is necessary: a) ↓ C (H + ) ; b) C (H + ) ; c) ↓ t; d) r. A 5. To shift the chemical equilibrium in the system Fe 3 O 4 (t.) + CO (g.) ↔ 3FeO (t.) + CO 2 (g.) - Q does not affect: a) ↓С (СО); b) ↓С (СО2); c) t; d) r. A 6. Chlorine in the reaction 2KBr + Cl 2 \u003d Br 2 + 2KCl a) is a reducing agent; b) does not change the degree of oxidation; c) is an oxidizing agent; d) oxidized. A 7. Chloride ions are formed during dissociation in an aqueous solution: A) KClO 3 ; b) CCl 4 ; c) NaClO; d) CuOHCl. A 8. Electrolytes are each of two substances: a) NaOH, CH 3 COONa; b) Fe 2 O 3 , CH 3 COOH; c) BaCl 2 , C 2 H 5 OH; d) C 6 H 12 O 6, CaCO 3. A 9. Abbreviated Fe ionic equation 2+ + 2OH - \u003d Fe (OH) 2 ↓ corresponds to the interaction: a) Fe(NO 3 ) 3 + KOH; b) Na 2 S + Fe (NO 3) 2; c) FeSO 4 + LiOH; d) Ba (OH) 2 + FeCl 3; A 10. The solution has an alkaline reaction of the medium: a) MgSO 4 ; b) KI; c) AlCl 3 ; d) Na 2 SO 3. | IN 1. In the above scheme H 2 S + Cl 2 + H 2 O → HCl + H 2 SO 4 determine the oxidation state of each element and arrange the coefficients using the electronic balance method. IN 2. Establish a correspondence between the name of the salt and its ability to hydrolyze. SALT NAME HYDROLYSIS ABILITY a) chromium sulfide (3); 1) hydrolyzed by cation; b) aluminum chloride; 2) is hydrolyzed by the anion; c) potassium sulfate; 3) hydrolyzed by cation and anion; d) sodium phosphate. 4) does not hydrolyze. From 1. Aluminum carbide was dissolved in 250 g of a 20% sulfuric acid solution. The methane released at the same time occupied a volume of 4.48 l (n.o.). Calculate the mass fraction of sulfuric acid in the resulting solution. |
Preview:
Examination No. 3
Substances and their properties
1 option
Part A | Part B and C |
A1. General formula of oxides: a) E x O y; b) M(OH) n ; c) H x Co; d) M x (Ko) y. A2. The general formula of saturated monohydric alcohols: a) NH3; b) PH 3 ; c) AsH 3 ; d) SbH 3 . a) CH 3 COOH; b) C 2 H 5 COOH; c) C 15 H 31 COOH; d) HCOOH. A5. Ionic reaction equation H+ + OH - \u003d H 2 O corresponds to the interaction: a) potassium hydroxide and nitric acid; b) barium hydroxide and sulfuric acid; c) lithium hydroxide and barium chloride; d) ammonia and hydrobromic acid. A6. Ethylamine can be obtained by interaction: a) ethane with nitric acid; b) ethane with a solution of potassium permanganate; c) ethyne with water; d) nitroethane with hydrogen. A7. Beryllium hydroxide interacts with matter: a) NaCl; b) NO; c) H 2 O; d) KOH. A8. Formulas of interaction products conc. H 2 SO 4 with silver: a) H 2 and Ag 2 SO 4; b) SO 2, H 2 O and Ag 2 SO 4; c) H 2 S, H 2 O and Ag 2 SO 4 ; d) there is no reaction. A9. In the chain of transformations 2 H 4 → X → CH 3 SON substance X is: a) C 2 H 6; b) C 2 H 5 OH; c) CH 3 COOH; d) CH 3 OH. A10. Specify the transformation consisting of 1 stage: a) C 2 H 6 → C 2 H 5 OH; b) CH 4 → C 6 H 6; c) FeCl 2 → Fe(OH) 3; d) СuO→Cu. | IN 1. Set match: IN 2. With which of the proposed substances: magnesium, nitric acid, oxygen, calcium hydroxide - will react: a) hydrochloric acid; b) methylamine? Write the appropriate reaction equations. C1. How many grams of salt are obtained by reacting a solution of sodium hydroxide weighing 10 g with a solution of nitric acid weighing 18.9 g? |
Examination No. 3
Substances and their properties
Option 2
Part A | Part B and C |
A1. General formula for bases: a) E x O y; b) M(OH) n ; c) H x Co; d) M x (Ko) y A2. The general formula of limiting monobasic carboxylic acids: a) R - OH; b) R - NH 2; c) RCOOH; d) NH 2 - R - COOH. A3. The main properties are most pronounced in a substance whose formula is: a) CH 3 NH 2 ; b) C 2 H 5 NH 2; c) C 6 H 5 NH 2; d) (C 6 H 5 ) 2 NH 2 . A4. Acidic properties are most pronounced in a substance whose formula is: a) HNO 2 ; b) HPO 3 ; c) HASO 3 ; d) HNO 3 . A5. Ionic reaction equation for CO 3 2- + 2H + = H 2 O + CO 2 corresponds to the interaction: a) sodium carbonate and acetic acid; b) calcium carbonate and nitric acid; c) calcium bicarbonate and hydrochloric acid; d) barium carbonate and formic acid. A6. Chromium(III) hydroxide can be obtained by interaction: a) chromium chloride (3) with calcium hydroxide; b) chromium nitrate (3) with copper hydroxide (2); c) chromium oxide (3) with sulfuric acid; d) chromium oxide (2) with hydrochloric acid. A7. Aminoacetic acid interacts with the substance: a) CO 2 ; b) KNO 3 ; c) H 2 ; d) HCl. A8. Formulas of interaction products conc. HNO 3 with zinc: a) H 2 and Zn(NO 3 ) 2 ; b) NO 2 , H 2 , Zn(NO 3 ) 2 ; c) NO, H 2 O, Zn (NO 3 ) 2 ; d) there is no reaction. A9. In the chain of transformations CH 3 COH → X → CH 3 COOC 2 H 5 substance X is: a) C 2 H 6 (OH) 2; b) C 3 H 7 COOH; c) CH 3 OH; d) CH 3 COOH. A10. Specify a transformation consisting of 2 stages: a) C 2 H 6 → C 4 H 10; b) CH 4 →CH 3 Cl; c) Cu→CuCl 2 ; d) C 3 H 8 → C 3 H 7 NO 2 | IN 1. Set match: IN 2. With which of the proposed substances: calcium, sulfuric acid, carbon dioxide, sodium carbonate - will react: a) barium hydroxide; b) acetic acid? Write the appropriate reaction equations. C1. How many grams of salt is obtained by reacting a solution of sodium hydroxide weighing 4 g with a solution of hydrochloric acid weighing 18.25 g? |
Preview:
Test in chemistry for grade 11 (profile) on the topics: "Structure of the atom", "Chemical bond"
Explanatory note
The control work was compiled for students of the 11th grade (profile) and is designed for 45 minutes. The work consists of three parts: part A - tasks of the basic level of complexity; parts B - tasks of an increased level of complexity; parts C - tasks of a high level of complexity. In part A - 10 tasks with the choice of the correct answer. Each task is worth 1 point. Part B consists of two tasks that are worth 2 points. Part C includes one task, for which 4 points are given.
The text of the control work was developed on the basis of thematic tests by V.N. Doronkin and textbook D.Yu. Dobrotin "Chemistry. Grade 11. Control work in a new format.
Objectives of the control work:
1) To control the knowledge of students in grade 11 on the topics: "Structure of the atom", "Chemical bond".
2) Continue preparing students for the exam in chemistry.
Requirements (skills) tested by job tasks:
1) Determine the number of electrons at the external level and the number of energy levels in the atoms of chemical elements.
2) Determine the atom or ion by the electronic formula.
3) Apply knowledge about the patterns of changes in the properties of atoms, simple substances and compounds formed by chemical elements within the main subgroups and periods of the Periodic Table of D.I. Mendeleev.
4) Distinguish types of chemical bonds from each other.
5) Determine the type of crystal lattice.
6) Know the features of substances of molecular and non-molecular structure.
7) Write down the formulas of higher oxides and hydroxides.
8) Compose electronic graphic formulas of atoms of chemical elements.
1 option
Part A | Parts B and C |
A1. The number of energy layers and the number of electrons in the outer energy layer of the selenium atom are equal, respectively: a) 4, 6; b) 3, 6; c) 4, 7; d) 3, 7. A2. Electronic formula 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 has an element atom: a) Va; b) Mg; c) Ca; d) Sr. A3. The chemical elements are arranged in ascending order of their atomic radii in the following order: a) Zn, Cd, Ca; b) Br, Cl, F; c) In, Sn, Sb; d) Br, Se, As. A4. Higher oxide composition E 2 O 3 form all the elements: a) ΙΙΙA groups; b) ΙVA groups; c) VΙA groups; d) VΙΙA groups. A5. In the HCl molecule, the chemical bond is: A6. Compounds with covalent non-polar and ionic bonds are respectively: a) N 2 and O 3; b) N 2 and NO; c) N 2 and NaCl; d) N 2 and CaSO 4. A7. The number of σ-bonds in the ethine molecule is: a) 5; b) 4; at 3; d) 6. A8. Each of the two substances has an ionic crystal lattice: a) NaCl, H 2 S; b) KF, H 2 O; c) HNO 3 , Cs 2 S; d) Na 2 CO 3, K 2 S. A9. Iodine has a crystal lattice: a) ionic; b) nuclear; c) molecular; d) metal. A10. The non-molecular structure has: a) fullerene; b) crystalline sulfur; c) carbon dioxide; d) diamond. | IN 1. IN 2. The increase in the basic properties of higher hydroxides occurs in the series of the elements that form them: 1) Na → Mg → Al; 2) As → P → N; 3) P → S → Cl; 4) B → Be → Li; 5) Mg → Ca → Ba. C1. Compose the electronic graphic formula of the sulfur atom in the ground state. Write down the formulas of higher oxide and sulfur hydroxide, what properties do these compounds have? Determine the type of chemical bond in these compounds. |
Test in chemistry for grade 11 (profile)
The structure of the atom. chemical bond
Option 2
Part A | Parts B and C |
A1. The number of energy layers and the number of electrons in the outer energy layer of an iron atom are equal, respectively: a) 4, 2; b) 4, 8; c) 4, 6; d) 4, 1. A2. Electronic formula 1s 2 2s 2 2p 6 3s 2 3p 6 corresponds to the particle: a) Li + ; b) K + ; c) Cs + ; d) Na + . A3 . The chemical elements are arranged in decreasing order of their atomic radii in the following order: a) Ba, Cd, Ra; b) In, Pb, Sb; c) Cs, Na, H; d) Br, Se, As. A4 . Higher Oxide Composition EO 2 form all the elements: a) ΙVA groups; b) ΙΙA groups; c) 4 periods; d) 2 periods. A5. In a CO 2 molecule chemical bond: a) ionic; b) covalent polar; c) covalent non-polar; d) hydrogen. A6. Compounds with covalent polar and covalent non-polar bonds are respectively: a) I 2 and H 2 Te; b) HBr and N 2 ; c) Fe and HF; d) CO and SO 2. A7. The number of π bonds in an ethene molecule is: a) 1; b) 4; in 2; d) 3. A8. The molecular structure has each of the compounds: a) H 2 O, K 2 SO 4; b) C 6 H 12 O 6, NH 3; c) HCl, KNO 3 ; d) BaO, Na 2 CO 3. A9. Stearic acid has a crystal lattice: a) nuclear b) ionic; c) metal; d) molecular. A10. The ionic structure has an oxide: a) silicon; b) cesium; c) carbon (ΙV); d) nitrogen (ΙV). | IN 1.Establish a correspondence between the formula of a substance and the type of chemical bond in it. B2.The increase in the acidic properties of higher hydroxides occurs in the series of the elements that form them: 1) Al → Si → P; 2) S → Se → Te; 3) Cl → Br → I; 4) B → C → N; 5) Mg → Ca → Sr. C1.Write the electronic graphic formula of the calcium atom in the ground state. Write down the formulas of higher oxide and calcium hydroxide, what properties do these compounds have? Determine the type of chemical bond in these compounds. |
Preview:
1 option
Part A.
A1. The particles contain the same number of electrons:
1) Al3+ and N3-
2) Ca2+ and Cl5+
3) S0 and Cl-
4) N3- and R3-
A2. Chemical bonding in methane and calcium chloride, respectively
1) covalent polar and metallic;
2) ionic and covalent polar;
3) covalent non-polar and ionic;
4) covalent polar and ionic.
A3. The molecular structure has
1) silicon(IV) oxide;
2) barium nitrate;
3) sodium chloride;
4) carbon monoxide(II).
A4.Zinc interacts with the solution
1) copper(II) sulfate;
2) potassium chloride;
3) sodium sulfate;
4) calcium nitrate.
A5. Aluminum hydroxide reacts with each of two substances:
1) KOH and Na2 SO4 ;
2) HCl and NaOH;
3) CuO and KNO3 ;
4) Fe2 O3 and HNO3 .
A6. In the transformation scheme: Fe →X1FeCl3 → x2Fe(OH)3 substances X1 and X2 are respectively
1)Cl2 and Cu(OH)2 ;
2) CuCl2 (solution) and NaOH(solution);
3)Cl2 and NaOH(solution);
4) HCl and H2 Oh
A7. Cis- and trans-isomerism is characteristic of:
1) butene-1; 2) butene-2;
3) butyne-1; 4) butina-2.
A8. Both nitric acid and copper hydroxide (2) will interact
1) phenol;
2) glycerin;
3) ethanol;
4) methyl acetate.
Part B.
IN 1. Establish a correspondence between the class of inorganic substances and the chemical formula of the substance.
Class of inorganic substances | Chemical formula |
A) basic oxide; B) acid oxide; B) amphoteric oxide; D) acid. | 1) B2 O3 ; 2) BaO; 3)H3 PO3 ; 4) ZnO; 5) Zn(OH)2 ; 6) Na2 ZnO2 . |
IN 2. Establish a correspondence between the salt formula and the product formed at the cathode during the electrolysis of its aqueous solution.
AT 4. Establish a correspondence between the formula of a substance and the reagents, with each of which it can interact.
Substance formula | Reagents |
A) HCl; B) K2 SiO3 ; B) Na2 CO3 ; D) CuCl2 . | 1) Ag, H3 PO4 , MgCl2 ; 2) H2 SO4 , HCl, CaCl2 ; 3) NaOH, Fe, Na2 S; 4)H2 SO4 , NaOH, CuO; 5) AgCl, SiO2 , H2 |
Part C.
Na2 SO3 + … + KOH → K2 MNO4 + … + H2 O
C2. Determine the mass fractions (in%) of iron (II) sulfate and aluminum sulfide in the mixture, if when treating 25 g of this mixture with water, a gas was released that completely reacted with 960 g of a 5% copper sulfate solution.
Final testing for the course of grade 11 profile
Option 2
Part A.
A1. In the series of elements Na→ Mg→ Al→ Si
1) the radii of atoms decrease;
2) the number of protons in the nuclei of atoms decreases;
3) the number of electron layers in atoms increases;
4) the highest degree of oxidation of atoms decreases.
A2. The oxidation state +7 chlorine has in the compound:
1) Ca(ClO2 ) 2 ;
2) HClO3 ;
3) NH4 Cl;
4) HClO4 .
A3. Which of the following oxides reacts with hydrochloric acid but does not react with sodium hydroxide?
1) CO;
2) SO3 ;
3) ZnO;
4) MgO.
A4. Barium carbonate reacts with a solution of each of the two substances:
1) H2 SO4 and NaOH;
2) NaCl and CuSO4 ;
3) HCl and CH3 COOH;
4) NaHCO3 and HNO3 .
A5. The largest amount of sulfate ions is formed in solution upon dissociation of 1 mol:
1) sodium sulfate;
2) copper(II) sulfate;
3) aluminum sulfate;
4) magnesium sulfate.
A6. Reduced ionic equation H+ + OH- = H2 About match interaction
1) H2 SO4 with NaOH;
2) Cu(OH)2 with HCl;
3) NH4 Cl with KOH;
4) HCl with HNO3 .
A7. For the human body, each of the two ions is the most toxic:
1) K+ and Pb2+
2) Na+ and Cu2+
3) Cu2+ and Hg2+
4) Ca2+ and Hg2+ .
A8. The reaction rate of nitrogen with hydrogen will decrease when:
1) lowering the temperature;
2) increase in nitrogen concentration;
3) the use of a catalyst;
4) pressure increase in the system.
Part B.
IN 1. Establish a correspondence between the name of the substance and the class of inorganic compounds to which it belongs.
IN 2. Establish a correspondence between the salt formula and the product formed on an inert anode during the electrolysis of its aqueous solution.
Salt Formula | Products on the anode |
A) Rb2 SO4 ; B) CH3 COOK; B) BaBr2 ; D) CuSO4. | 1) methane; 2) sulfur dioxide; 3) oxygen; 4) hydrogen; 5) bromine; 6) ethane and carbon dioxide. |
B3. Establish a correspondence between the name of the salt and its relation to hydrolysis.
AT 4. Match the reactants with the reaction products.
Reactive Substances | reaction products |
A) Al and KOH (solution); B) Al and H2 SO4 (razb.); B) Al2 S3 and H2 O; D) Al and H2 O | 1) aluminum hydroxide and sulfur; 2) aluminum hydroxide and hydrogen sulfide; 3) potassium tetrahydroxoaluminate and hydrogen; 4) aluminum sulfate and hydrogen; 5) potassium aluminate and aluminum oxide; 6) aluminum hydroxide and hydrogen. |
Part C.
C1. Using the electron balance method, write the equation for the reaction
FeSO4 + KClO3 + … → K2 FeO4 + … + K2 SO4 + …
Determine the oxidizing agent and reducing agent.
C2. Aluminum carbide was dissolved in a 15% sulfuric acid solution weighing 300 g. The methane released at the same time occupied a volume of 2.24 l (n.o.). Calculate the mass fraction of sulfuric acid in the resulting solution.
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Bioinorganic chemistry of toxic metal ions
39
Pb2+ « Hg2+ « Cu2+ ~ Alkali metal ions>Cr2+ « Cd2+ ~ Ca2+> Lanthanides « Mn2+ « Zn2+>Fe2+ « Co2+ « Mg2^+>>Ni2+>Be2+>Fe3+>Al3+>>Co3+ »»>Cr3+
Each inequality sign means a tenfold decrease in the rate, starting (at 25°C) from rate constants of the order of 109 s-1 at the very beginning of the series and decreasing to approximately -metal ions, yet they reflect the relative exchange rates of other monodentate ligands, while ligands prone to chelation exchange more slowly.
The above series of relative exchange rates indicates that some of the most strongly binding metal ions also undergo ligand exchange. Examples are Pb2+, Hg2+, Cu2+ and Cd2+. As described in sect. 4.19, rapid exchange is an important feature of mercury toxicology. Ni2+ does not differ at all in terms of compound stability or ion size (see Table 2) from many other metal ions, for example, from Zn2+. The marked contrast that zinc is present in numerous mammalian enzymes and that nickel is known only for a small number of plant enzymes has surprised many investigators. The above series of exchange rates explain the reasons for this contrast, since Zn2+ exchanges its ligands 103 times faster than the Ni2+ ion does, and this is an important characteristic for a metal ion located at active binding sites of enzymes; an even slower exchange of the Al3+ ion is excluded in these cases.
4. Overview of metal ions
4.1. Introduction. This section provides general principles already known in the field of metal ion toxicity research. For the most part, the discussion is conducted on groups of the periodic table of elements. Since the need for metals and their toxicity are not directly related chemically, the necessary metal ions are not considered separately. Naturally, the emphasis is on the toxicity of metals specifically for humans. For many metal ions, acute toxicity occurs when a sudden "hit" with a large dose of metal; at the same time, other effects and symptoms appear than with chronic poisoning; chronic poisoning occurs when receiving low doses of the metal, but over an extended period of time.
A complete description of all symptoms of both acute and chronic toxicity is set out in two comprehensive guidelines and is a comprehensive guide and should be used for further information on metal ion toxicity. Regarding the toxicity of metal ions in the environment, you should refer to the book.
The most serious toxic effects of metal ions result from the inhalation of dust, usually occurring in an industrial plant. Particularly dangerous are particles with a diameter of 0.1-1 microns, which are effectively adsorbed by the lungs. Note that the lungs absorb metal ions, which then enter the liquid media of the body, ten times more efficiently than the gastrointestinal tract. Thus, for example, the greatest danger from radioactive plutonium-239 (which emits active a-particles with a half-life of 24.4 thousand years) comes not from the absorption of plutonium with food, but from the adsorption of plutonium powder by the lung tissue. Volatile metal compounds, such as carbonyl and alkyl compounds of mercury, lead, and tin, are easily absorbed by the lungs and can cause acute metal poisoning. Hence the conclusion: any inhalation with metal ions should be avoided! Because inhalation events are relatively rare and localized, they will not be given as much attention in this section as they are for the more common and less obvious metal ion ingestion toxicity. Information about the toxicity of metal ions entering the body through the respiratory tract, the reader will find in monographs.
4.2. Alkali metal ions. None of the alkali metals are particularly toxic. Homeostasis maintains the concentration of both essential Na+ and K+ ions (Table 1) at normal physiological levels. The role of both of these elements in digestion is described in the work. In addition to their specific action, these metal ions play two crucial roles in living organisms: they determine the osmotic balance on both sides of the membrane and provide positive counterions for anions such as HPO42, HCO3" and organic molecules, many of which are just anions . Thus, Na+ and K+, respectively, serve as the main intercellular and intracellular counterions.
Other alkali metal ions can compete with Na+, K+ ions in some physiological processes; of these, Li+ is the most toxic. In the human body, the intracellular fluid, along with K+ ions, contains approximately 0.3 g of Rb+. Small amounts of Cs+ may also be present; significant
