Chemistry. Final Stageversiysk Olympiad Schoolchildren in Chemistry School Olympiad in Chemistry

in 2017-2018 academic year

School stage

8th grade

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‒

We wish you success!

Task 1. (8 points)

TEST. Select one correct answer

1. Conducting carbon, playing a major role in its natural cycle:

A) carbon monoxide; B) soot; C) oil; D) methane; E) carbon dioxide.

2. Pure water from the listed list is:

A) plumbing; B) spring; C) rain;

D) well; D) mineral.

3. From the listed chemical and physicochemical processes, select this for which the high temperature is not required:

A) firing; B) calcination; C) fermentation;

D) sintering; E) fusion.

4. Among the listed metal materials used for the manufacture of prize medals, tokens and coin signs, the alloy is

A) gold; B) silver; C) bronze; D) nickel; E) aluminum.

5. Which of the listed operations is not used in a chemical laboratory for separation and purification of substances?

A) recrystallization; B) supercooling; C) distillation; D) sublimation; E) rebelief.

6. Starting the movement from the upper left cell and moving horizontally (left or right) or vertical (up or down), go through all cells in such a way that the letters given in cells have turned out to be a rule on precautions when handling chemical reagents. Each cell can only be used once.

7. Decide the crossword, filling it with Russian names of chemical elements. The key word is the name of the Great Russian scientist, one of the creators of atomic molecular teachings.

1) C, 2) O, 3) Al, 4) n, 5) zn, 6) i, 7) p, 8) h, 9) pb

Task 2. (8 points)

1) Complete phrases: (a) the composition of the individual substance, in contrast to the composition of the mixture, __________ and may be expressed by Chemical__ __________; (b) __________ Unlike __________ I boil with constant __________.

2) Which of the two liquids - acetone and milk - is an individual substance, and what is the mixture?

3) You need to prove that the substance you have chosen (one of two in p. 2) is a mixture. Briefly describe your actions.

Task 3. (8 points)

Common substance "This complex substance is widespread in nature. Meets all over the globe. There is no smell. At atmospheric pressure, the substance may be only in gaseous and solid states. Many scientists believe that this substance affects the increase in the temperature of our planet. It is used in various industries, including the food industry. Used when steaming fires. However, in the chemical laboratory, they can not be hungry for burning metals, such as magnesium. Drinks cooked with this substance love children very much. But the constant consumption of such beverages can cause irritation of the stomach walls. "

1) Determine the substance based on its description.

2) What names of this substance are known to you?

3) Give the examples known to you and name the sources of formation of this substance.

Task 4. (8 points)

In the process of breathing, a person consumes oxygen and carbon dioxide exhales. The content of these gases in the inhale and exhaled air is given in the table.

	O 2 (% by volume)	CO 2 (% by volume)
Inhaled
Exhaled

The amount of inhalation-exhalation is 0.5 l, the frequency of normal breathing is 15 inhales in min.

1) How many oxygen liters consumes a person in an hour and how much does carbon dioxide highlight?

2) In class, the volume of 100 m 3 are 20 people. Windows and doors are closed. What will be the volumetric content of CO 2 in the air after a lesson with a duration of 45 minutes? (Completely safe content - up to 0.1%).

Task 5 (10 points)

In five numbered glasses, powders of the following substances were issued: copper, copper oxide (II), charcoal, red phosphorus and sulfur.

The students investigated the properties of the powdered substances issued, the results of their observations were presented in the table.

Stakana number	Color of substance		Changes observed when heating the heated air powder
		floats on the surface of the water	begins to fly
		sun in water	does not change
		floats on the surface of the water	melts, burns with a bluish flame, a colorless gas with a sharp smell is formed when burning
	dark red	4 sinking in water	lights a bright white flame, when burning is formed thick smoke white
		sun in water	gradually worn

1) Determine in which glass is each of the substances issued for the study. Justify the answer.

2) Write the reaction equations that proceed with the participation of the substances issued when they are heated in air.

3) It is known that the density of substances in glasses No. 1 and No. 3, more water density, i.e., these substances should be sinking in water. However, the powders of these substances float on the surface of the water. Offer a possible explanation for this.

All-Russian Olympiad of Schoolchildren in Chemistry

in 2017-2018 academic year

School stage

Grade 9.

Dear member!

When performing tasks you have to do a certain job that it is better to organize in the following way:

‒ read the task carefully;

‒ if you answer theoretical question or solve the situational task, think about and specify a specific answer (the answer should be brief, its contents enter into a reserved field, write a clear and picking up).

For each correct answer, you can get a number of points defined by members of the jury, but not higher than the specified maximum assessment.

When executing tasks, you can use the calculator, periodic table and solubility table. The tasks are considered to be fulfilled if you have passed them in time to the audience.

We wish you success!

Task 1. (6 points)

In which particle contains 11 protons, 10 electrons and 7 neutrons? Determine its composition, charge, relative molecular weight. Write the formulas of two compounds, which includes this particle.

Task 2. (10 points)

The following substances are given: copper sulfate (II), barium chloride, iron oxide (III), carbon oxide (IV), sodium oxide, silver, iron, sodium carbonate, water. Which of these substances will react with each other directly or in aqueous solution at room temperature? Bring the equations of five possible reactions. For each reaction, specify which type it applies.

Task 3. (10 points)

Calcium chips weighing 4.0 g was punctured in the air, and then threw into the water. In the dissolution of chips in the water, 560 ml of gas was distinguished (n. Y.), Which practically does not dissolve in water.

1) Write the reaction equations.

2) Determine how many grams have increased shavings with calcination.

3) Calculate the composition of the crumpled chips in mass percent.

Write the reaction equations with which using these calcium, phosphorus and oxygen substances, can be obtained by calcium phosphate.

Task 4.(8 points)

To dissolve 7.8 g of metal, 40 ml of 20% hydrochloric acid is required (density of 1.095 g / ml), while a bivalent metal salt is formed. Hydrogen released completely reacts from 6.4 g of treacured metal oxide. Determine which metals were used in these reactions.

Task 5. (8 points)

In four numbered tubes there are solutions of barium chloride, sodium carbonate, potassium sulfate and chloride acid. Invite the method of recognition of substances without the use of additional reagents. Write the reactions equations.

School stage

Grade 10

Dear member!

When executing tasks you have to do a certain job that is better to organize as follows:

‒ read the task carefully;

For each correct answer, you can get a number of points defined by members of the jury, but not higher than the specified maximum assessment.

When executing tasks, you can use the calculator, periodic table and solubility table. The tasks are considered to be fulfilled if you have passed them in time to the audience.

We wish you success!

Task 1. (10 points)

In ten numbered glasses, powders of the following substances were issued: copper, copper oxide (II), charcoal, red phosphorus, sulfur, iron, sodium chloride, sugar, chalk, malachite (fastened copper (II) carbonate). The students investigated the properties of the powdered substances issued, the results of their observations were presented in the table.

Stakana number	The color of the studied substance	"Behavior" of powder when placing it in a glass with water	Changes observed when heating the studied powder in the spoon with the help of alcohol
			practically does not change
		sinking in water is gradually dissolved	melting, darkens, gradually charred
		sinking in water, not dissolved	practically does not change
			melting, burns bluish flame
		sinking in water, not dissolved	gradually worn
	dark red	sinking in water, not dissolved	lights bright white flame
		sinking in water, not dissolved	gradually worn
	dark grey	sinking in water, not dissolved	darkens, particles in flames are rare
		particles float on the surface of the water, do not dissolve	begins to fly
		sinking in water, not dissolved	practically does not change

1. Determine which one from the substances issued for the study are located on the number of the glass. Justify the answer.

2. Which of the issued substances react with hydrochloric acid with gas release? Make appropriate equations of reactions.

3. It is known that the density of substances in glasses No. 4 and No. 9, more water density, i.e., these substances should be sinking in water. However, the powders of these substances float on the surface of the water. Offer a possible explanation for this fact.

4. It is known that three substances issued are electrically conducted. What are these substances? Solving of which substance conducts electric current?

Task 2. (7 points)

Make all the isomers of the dichloroalcena of the C 3 H 4 CL 2

Task 3. (10 points)

Organic compound A contains 39.73% carbon and 7.28% hydrogen by weight. Determine the molecular formula of substance A and install its structural formula, if it is known that a quaternary carbon atom includes its composition, and the density of the air vapor is 5.2. Name the organic compound A along the systematic nomenclature. Invite the method of obtaining A.

Task 4. (10 points)

Restore the left of the equations:

.... + ... + ... \u003d Na 2 SO 4 + 2AG ↓ + 2HNO 3

.... \u003d Na 2 S + 3NA 2 SO 4

.... + ... + ... \u003d 3NA 2 SO 4 + 2mno 2 ↓ + 2KOH

.... + ... \u003d POCL 3 + SOCL 2

.... + ... + ... → 2H 2 SO 4

Task 5. (10 points)

Viewing reagents in the laboratory, the young chemist found an unsigned jar with a white powder without smell. To study its properties, the young chemist gently weighed 10.00 grams and divided them exactly 5 parts, with each part he spent the following experiments:

Observe number	Structure of experiment	Observations
		Well soluble in water. The solution was painted red
		Stormy gas
	Carefully made part of the hitch in the flame burner	Flame burner painted in purple color
		3.43 g of white sediment was falling, insoluble in acids and alkalis
		The test tube was heated. Visible signs of reaction was not observed

1. Determine the composition of the white powder. Answer confirm with the calculation.

2. For experiments 2, 4, 5, give the appropriate reaction equation.

3. What happens when the white powder is heated? Bring the impact response equation.

All-Russian Olympiad Schoolchildren in Chemistry in 2017-2018 Uch. year

School stage

Grade 11

Dear member!

When executing tasks you have to do a certain job that is better to organize as follows:

‒ read the task carefully;

For each correct answer, you can get a number of points defined by members of the jury, but not higher than the specified maximum assessment.

When executing tasks, you can use the calculator, periodic table and solubility table. The tasks are considered to be fulfilled if you have passed them in time to the audience.

We wish you success!

Task 1. (10 points)

The two elements in the same period and in the same group of the periodic system (in its short variant) form each other a single stable binary connection with a mass fraction of one of the elements of 25.6%. This compound is well soluble in water, and when passing into its solution, the gaseous ammonia drops a white precipitate, gradually dark in air. Name the elements, determine the formula of the substance and write the reactions equations.

Task 2. (10 points)

How from natural limestone get benzoethyl ether C 6 H 5 COOC 2 H 5 according to the following scheme:

Caco 3 → CAC 2 → C 2 H 2 → ... → C 6 H 5 C 2 H 5 → C 6 H 5 COOH → C 6 H 5 COOC 2 H 5

Write the reaction equations, indicate the conditions for the reaction.

Task 3. (10 points)

White solid, self-relieving at room temperature or under mechanical exposure, has such an elemental composition: ω (n) \u003d 45.16%, ω (O) \u003d 51.61%, ω (H) \u003d 3.23%. The substance is well soluble in water and is a weak two-axis acid.

A. Place the formula of substance, name it, write the acid dissociation equation.

B. Picture a structural formula of the acid.

B. Record the reaction equations: a) the thermal decomposition of this acid, b) of its interaction with air oxygen, c) of the interaction of it with alkali

Task 4. (8 points)

Young Chemist Vasya decided to explore a certain alloy that was inherited from her grandmother. To begin with, Vasya tried to dissolve the alloy in hydrochloric acid, but it found that no dissolution occurs. Then he tried to dissolve it in hot concentrated nitric acid. At the same time, the alloy collapsed, the solution was painted in a blue color, but a colored precipitate remained at the bottom, which did not dissolve even with long heating in nitric acid. Vasya filtered the precipitate and dried it. By placing the powder into a crucible and heating it to melting, and then cooling, Vasya immediately understood which substance was an insoluble sediment.

1. What two metals is the alloy that explored Vasya?

2. How to dissolve the precipitate formed when heating alloy in nitric acid? Bring the reaction equation.

3. How to highlight the second component of the alloy from the blue solution obtained after the reaction with nitric acid? Give the necessary reaction equations

Task 5. (10 points)

An 8th grade student when conducting practical work "Operating oxygen and studying its properties" assembled an instrument for obtaining oxygen by the method of displacing water. At the same time, he violated one of the requirements of the instruction - did not place a piece of cotton swab in a test tube near the gas pipe. When driving potassium permanganate, water in a crystallizer was painted in red-purple color. When the oxygen is collected, a part of the painted solution fell into a flask with a gas. In it, the student is burned sulfur. In this case, the red-violet color of the solution disappeared, and a colorless solution was formed. Deciding to investigate the resulting solution, the student adhered a part of the painted solution from the crystallizer into it. And again the color changed - the dark brown sediment fell out of the unknown substance.

1. Record the equation of the decomposition of potassium permanganate.

2. What substance got into a crystallizer with water?

3. Why did the solution discolored when burning sulfur? Write down the reaction equation.

4. Call the substance that fell into the sediment. Write down the reaction equation.

Keys

All-Russian Olympiad Schoolchildren in Chemistry in 2017-2018 Uch. year

School stage

Grade 8 (max. 42 points)

Task 1. (8 points)

Test 2.5 Point (0.5 points for each task)

6. Rule -Chemical reagents can not taste. - 1 point

7. Crossword 4.5 points(0.5 points per each element)

1 - carbon, 2- oxygen, 3-aluminum, 4-outshot, 5-zinc, 6 - iodine, 7- phosphorus, 8- hydrogen, 9 - lead.

Task 2. (8 points)

1) (a) the composition of the individual substance, in contrast to the composition of the mixture, constant and can be expressed by the chemical formula; (b) Individual substance, in contrast to the mixture of substances, pins at a constant temperature. (4 points)

2) acetone - an individual substance, milk - a mixture. (2 points)

3) Let's place the drop of both liquids in the microscope. Milk under the microscope will be inhomogeneously. This is a mixture. Acetone under the microscope will be homogeneous.

Another possible solution: acetone boils at a constant temperature. Water evaporates from milk when boiling, the film is formed on the surface of milk - foam. Other reasonable evidence is also accepted. (2 points)

Task 3. (8 points)

1. The substance is called carbon dioxide (carbon oxide (IV)) (2 points ). A possible answer is water - to be considered wrong. Water does not irritate the stomach.

2. Dry ice, carbon dioxide, coal anhydride (3 points: 1 point for each answer).

3. Carbon dioxide is used in the production of carbonated drinks, sugar production, when steaming fires as refrigerant, etc. is formed when animal than organisms, fermentation, rotting of organic residues, in the production of negascinated lime, burning organic substances (peat, wood, natural gas, kerosene , gasoline, etc.) . (One point for an example, but not more than 3 points).

Task 4. (8 points)

1) For an hour, a person makes 900 inhales and 450 l of air passes through the lungs. (1 point) Not all inhaled oxygen is consumed, but only 21% - 16.5% \u003d 4.5% of the air volume, i.e. approximately 20 l. (1 point )

Carbon dioxide is distinguished as much as oxygen is spent, 20 liters. (1 point)

2) in 45 minutes (3/4 hours) 1 person allocates 15 liters of CO2. (1 point)

20 people allocate 300 liters CO2 . (1 point)

Initially, the air contained 0.03% of 100 m3, 30 liters CO2, (1 point)

after the lesson, it became 330 liters. CO2 content: 330 l / (100 000 l) · 100% \u003d 0.33% (2 points ) This content exceeds a safe threshold, so the class must be used.

Note. The calculation in the second question uses the answer to the first question. If an incorrect number is obtained in the first question, but then the right actions are performed with it in the second paragraph, the maximum score is made for this item, despite the wrong answer.

Task 5. (10 points)

1) In a glass No. 1 is coal powder. Black color, air smoothing.

No. 2 - copper oxide (II); It has black, when heated does not change.

№ 3 - sulfur; Yellow color, characteristic combustion with the formation of sulfur gas.

No. 4 - red phosphorus; Dark red color, characteristic combustion with the formation of phosphorus oxide (V).

№ 5 - copper; Red color; The appearance of black color when heated due to the formation of copper oxide (II).

(0.5 points for each correct definition and another 0.5 points for a reasonable justification of only 5 points)

2) C + O2 \u003d CO 2 S + O2 \u003d SO 2 4P + 5O 2 \u003d 2P 2 O 5 2CU + O 2 \u003d 2CUO (1 point for each equation is only 4 points)

3) in glasses No. 1 and No. 3 are the powders of charcoal and sulfur, respectively. Particles of wood coal are permeated with capillaries filled with air, thus, their average density is less than 1 g / ml. In addition, the surface of the coal, as well as the surface of the sulfur, is not wetted by water, i.e. is hydrophobic. Small particles of these substances are held on the surface of the water of the surface tension. (1 point)

Keys

All-Russian Olympiad Schoolchildren in Chemistry in 2017-2018 Uch. year

School stage

Grade 9 (max. 42 points)

Task 1. (6 points)

1. Protons per 1 more than electrons. Consequently, the particle has a charge of +1. Neutrons - less than protons, therefore, the particle includes hydrogen atoms in which neutrons are not at all. 11 - 7 \u003d 4 is the minimum number of H atoms. Without hydrogens, 7 protons and 7 neutrons will remain - this is a nitrogen atom-14: 14N. Composition of a particle: 14NH4 + - ammonium ion ( 2 points )

Charge: 11 - 10 \u003d +1 (1 point)

Relative molecular weight: 11 + 7 \u003d 18 or 14 + 4 \u003d 18 (1 point)

Formulas: NH4CL, (NH4) 2CO3 or other ammonium salts (2 points)

Task 2 (10 points)

Possible reactions:

Na 2 O + H 2 O \u003d 2NAOH connections

Na 2 O + CO 2 \u003d Na 2 CO 3 Connections

BACL 2 + CUSO 4 \u003d BASO 4 + CUCL 2 exchange

2Cuso 4 + 2NA 2 CO 3 + H 2 O \u003d Cu 2 (OH) 2 CO 3 + CO 2 + 2NA 2 SO 4 exchange

Fe + Cuso 4 \u003d Cu + Feso 4 Replacement

Na 2 CO 3 + CO 2 + H 2 O \u003d 2NAHCO 3 connections

Na 2 O + H 2 O + CUSO 4 \u003d CU (OH) 2 + Na 2 SO 4 compounds and exchange

2NAOH + CO 2 \u003d Na 2 CO 3 + H 2 O Exchange

BACL 2 + Na 2 CO 3 \u003d Baco 3 + 2NACL Exchange

For each of the five equations - 2 points (1 point for substance, 0.5 points for coefficients, 0.5 points for the type of reaction).

(other formulations of the response are allowed, not distorting its meaning)

Task 3 (10 points)

When calculating calcium chips, a reaction occurs: 2CA + O 2 \u003d 2CAO (the condition that gas is practically not dissolved in water, eliminates the calcium reaction with nitrogen, which can lead to calcium nitride, hydrolyzing with the formation of NH 3.) Since calcium melts At high temperature, and the reaction product is also a refractory, metal oxidation at first occurs only from the surface. The calcined chips is a metal, outside the oxide layer. When placed in water and metal, and the oxide react with it: Cao + H 2 O \u003d Ca (OH) 2; Ca + 2H 2 O \u003d Ca (OH) 2 + H 2.

2) the amount of metal substance that has not entered into a reaction with oxygen is equal to the amount of substance of the gas distilled (hydrogen): N (Ca) \u003d n (H 2) \u003d 0.56 / 22.4 \u003d 0.025 mol. In total, in the original chips N (Ca) \u003d 4/40 \u003d 0.1 mol. Thus, 0.1-0.025 \u003d 0.075 mole of calcium entered into the reaction with oxygen, which is M (Ca) \u003d 0.075 * 40 \u003d 3 g. The increase in the mass of chips is associated with the addition of oxygen. The mass of oxygen entered into a calcium reaction is M (O 2) \u003d 32 * 0.0375 \u003d 1.2. So, the mass of chips after calcination increased by 1.2 g.

3. The calcined chips consists of calcium (0.025 mol) weighing 1 g and calcium oxide (0.075 mol) weighing 4.2 g. Composition in mass percentage: CA - 19.2%; Cao - 80.8%. Evaluation system:

1. For each response equation 1 point - 3 points

2. For the calculation of the amount of hydrogen substance - 1 point

For the correct answer - 3 points

3. For the correct answer - 3 points

Task 4 (8 points)

1) determine the amount of hydrogen substance

m (HCl) \u003d w · ρ · v \u003d 0.2 · 1,095 · 40 \u003d 8.76 g

ν (HCl) \u003d M V-V / M B-Va \u003d 8.76 / 36.5 \u003d 0.24 mol (2 points)

2) ME + 2HCl \u003d Mecl 2 + H2

a) ν (me) \u003d ν (H 2) \u003d 0.5ν (HCl) \u003d 0.5 · 0.24 \u003d 0.12 mol

b) m (me) \u003d m in-v / ν \u003d 7.8 / 0,12 \u003d 65g / mol (2 points)

Metal - zinc (1 point)

3) IM 2 O 3 + 3 H 2 \u003d 2MA + H 2

a) ν (i 2 o 3) \u003d 1 / 3ν (H 2) \u003d 0.12 / 3 \u003d 0.04 mol

b) m (me 2 o 3) \u003d m in v / ν \u003d 6.4 / 0.04 \u003d 160g / mol

160 \u003d 2AM + 3 · 16 Ame \u003d 56 (2 points)

Metal - iron (1 point)

Task 5. (8 points)

Compiled table of a mental experiment


	white sediment drops	white sediment drops	without changes
white sediment drops		Without changes	gas is released without color and smell
white sediment drops	Without changes		Without changes
Without changes	Gas is released without color and smell	Without changes

The equations of reactions in molecular and ion form are given:

BACL 2 + Na 2 CO 3 → Baco 3 ↓ + 2NACL;

Na 2 CO 3 + 2HCl → 2NACL + CO 2 + H 2 O

BACL 2 + K 2 SO 4 \u003d BASO 4 ↓ + 2KCL;

Assessment guidelines

For drawing up a table - 1 point

For the table of a mental experiment - 4 points

For each correctly composed molecular equation of 1 point (3 equations) - 3 Point

Keys

All-Russian Olympiad Schoolchildren in Chemistry in 2017-2018 Uch. year

School stage

Grade 10 (max. 47 points)

Task 1. (10 points)

1. Glass No. 1 is sodium chloride. White color dissolves in water, practically does not change in air when heated.

№ 2 - sugar; White color dissolves in water, melts and gradually charred when heated.

№ 3 - chalk; White color does not dissolve in water.

No. 4 - sulfur; Yellow color, characteristic burning.

№ 5 - copper; Red color; The appearance of black color when heating in air due to the formation of copper oxide (II).

No. 6 - Red Phosphorus; Dark red; Characteristic combustion.

№ 7 - Malachite; green color; The appearance of black painting with thermal decomposition due to the formation of copper oxide (II).

№ 8 - iron; Dark gray; Damage when heated.

№ 9 - Charcoal; black color; Small when heated in air.

No. 10 - copper oxide (II); black color; No changes when heated.

0.5 points for each correct definition and reasonable justification. Maximum - 5 points.

2. Gaseous substances are released in the interaction of hydrochloric acid with chalk, malachite and iron:

Caco 3 + 2HCl \u003d CaCl 2 + CO 2 + H 2 O

(CuOH) 2 CO 3 + 4HCl \u003d 2CUCl 2 + CO 2 + 3H 2 O

Fe + 2HCl \u003d FECL 2 + H 2

3 points - 1 point for each equation

3. In glasses number 4 and No. 9 are respectively sulfur powders and charcoal. Particles of wood coal are permeated with capillaries filled with air, thus, their average density is less than 1 g / ml. In addition, the surface of the coal, as well as the surface of the sulfur, is not wetted by water, i.e. is hydrophobic. Small particles of these substances are held on the surface of the water of the surface tension. 1 point

4. Electric current is carried out copper, iron and coal. Sodium chloride solution conducts electric current, since NaCl - electrolyte. 1 point

Task 2. (7 points)

Trans-1,2-dichloropropen

Cis-1,2-dichloropropen

1,1- Dichloropropen

2.3 - dichloropropen

Trans-1,3-dichloropropen

Cis-1,3-dichloropropen

3,3-dichloropropen

7 points: 0.5 points per each structure, 0.5 points per each name.

Task 3. (10 points)

1) because The amount of mass fractions is not equal to 100%, therefore, there is still some residue in the molecule, the content of which is equal to:

100 – 39,73 – 7,28 = 52,99 %.

Molar mass of the substance: M (a) \u003d D Rest * M Rest \u003d 5.2 * 29 \u003d 151 g / mol.

The number of hydrogen atoms in the molecule A: 151 * 0.0728 / 1 \u003d 11.

The number of carbon atoms in the molecule A: 151 * 0.3973 / 12 \u003d 5.

The molar mass of the residue is 151 × 0.5299 \u003d 80 g / mol, which corresponds to one atom of bromine, consequently, the molecular formula of the substance BUT - C 5 H 11 Br.

2) The composition A includes a quaternary carbon atom, therefore, but has the following structure:

CH 3 - C - CH 2 BR 1-bromo-2,2-dimethylpropane

3) method of obtaining BUT:

CH 3 -C (CH 3) 2 -CH 3 + BR 2 \u003d CH 3 -C (CH 3) 2 -CH 2 BR + HBR

Evaluation system:

1) determining the amount of carbon atoms 1 point

Determination of the amount of hydrogen atoms 1 point

Definition of bromine 2 points

Molecular formula 1 point

2) Structure 2 points

Name 1 point

3) receiving reaction equation 2 points.

Task 4. (10 points)

Na 2 SO 3 + H 2 O + 2AGNO 3 \u003d Na 2 SO 4 + 2AG ↓ + 2HNO 3

4NA 2 SO 3 \u003d Na 2 S + 3NA 2 SO 4

3NA 2 SO 3 + H 2 O + 2KMNO 4 \u003d 3NA 2 SO 4 + 2MNO 2 ↓ + 2KOH

SO 2 + PCL 5 \u003d POCL 3 + SOCL 2

2SO 2 + 2H 2 O + O2 \u003d 2H 2 SO 4

For each equation - 2 points

Task 5. (10 points)

1. Coloring flame burner in purple color says that the desired powder is potassium salt. White sediment loss with excess barium chloride is a high-quality reaction to sulfate ion. But potassium sulfate (K 2 SO 4) has a neutral medium (salt is formed by a strong base and strong acid), and according to the experiment No. 1, the lanch stains the salt solution in red, which indicates the acidic reaction. Consequently, the sought salt - potassium hydrosulfate, KHSO 4. Check this by calculation: KHSO 4 + BACL 2 → BASO 4 ↓ + HCl + KCL

t. K. The initial jamming of 10.00 g, the young chemist divided into five equal parts, which means 2.00 g of salts entered the reaction:

n (khso 4) \u003d n (Baso 4) \u003d 2g / 136g / mol \u003d 0,0147mol;

m (Baso 4) \u003d 0,0147mol * 233g / mol \u003d 3.43g.

The resulting mass of barium sulfate coincides with the results of the experiment, therefore the white powder is really KHSO 4.

2. Reaction equations:

2KHSO 4 + K 2 CO 3 → 2K 2 SO 4 + CO 2 + H 2 O

KHSO 4 + BACL 2 → BASO 4 ↓ + HCl + KCL

KHSO 4 + KOH → K 2 SO 4 + H 2 O

3. Equation of decomposition reaction: 2khso 4 \u003d k 2 S 2 O 7 + H 2 O

Estimation system:

1) the conclusion about the presence of potassium ions - 1 point

The conclusion about the presence of sulfate ions - 1 point

Payment - 2 points

Salt formula - 1 point

2) 3 equations on 1 point - 3 points

3) Equation of the decomposition reaction - 2 points

Keys

All-Russian Olympiad Schoolchildren in Chemistry in 2017-2018 Uch. year

School stage

Grade 11 (Max. 48 points)

Task 1. (10 points)

Since the elements are located in the same period and in the same group of the periodic system, one of them is in the main subgroup, and the other in the side, i.e. is a D-metal. Judging by the solubility in water, the substance is a halide, which means that the metal is located in a side subgroup of the seventh group of the periodic system. Judging by the properties, this is a manganese, and the substance is MNBR 2.

Indeed, the mass fraction of manganese is equal to 55: 215 ≈ 0.256 \u003d 25.6%. Elements - Mn and Br, Substance - MnBr 2 (6 points: 2 points for each element, 2 points per substance).

Reaction equations:

MnBr 2 + 2NH 3 + 2H 2 O \u003d Mn (OH) 2 ↓ + 2NH 4 BR;

2mn (OH) 2 + O 2 \u003d 2mno 2 ↓ + 2H 2 O (4 points: 2 points for equation).

Task 2. (10 points)

Caco 3 + 4C \u003d CAC 2 + 3CO (calcination);

CAC 2 + 2H 2 O \u003d Ca (OH) 2 + C 2 H 2;

3C 2 H 2 \u003d C 6 H 6 (heating, catalyst - coal);

C 2 H 2 + 2H 2 \u003d C 2 H 6 (when heated, catalyst - platinum);

C 2 H 6 + Cl 2 \u003d C 2 H 5 Cl (when illuminated);

C 6 H 6 + C 2 H 5 CL \u003d C 6 H 5 C 2 H 5 + HCl (catalyst - aluminum chloride);

C 6 H 5 C 2 H 5 + 2K 2 CR 2 O 7 + 8H 2 SO 4 \u003d C 6 H 5 COOH + CO 2 + 2K 2 SO 4 + 2CR 2 (SO 4) 3 + 10H 2 O; C 2 H 5 Cl + NaOH \u003d C 2 H 5 OH + NaCl;

C 6 H 5 COOH + C 2 H 5 OH \u003d C 6 H 5 COOC 2 H 5 + H 2 O (when heated, catalyst - H 2 SO 4). Evaluation scheme:

per right transition from limestone to acetylene - 3 points;

for receipt of benzene from acetylene - 1 point;

for obtaining benzoic acid from benzene - 2 points;

for the preparation of ether by one or another method of benzoic acid - 4 points .

Task 3. (10 points)

A. Setting the formula of the substance.

Denote by the formula H x n y o z - x: y: z \u003d 3,23 / 1: 45,16 / 14: 51.61 / 16 \u003d 1: 1: 1;

the simplest formula of the HNO, but according to the condition, it is a two-axis acid, therefore it is logical to assume that its formula H 2 N 2 O 2 is nitric acid. The dissociation equation H 2 N 2 O 2 ↔ H + + HN 2 O 2 - ↔ 2H + + N 2 O 2 -2 (5 points)

B. Structural formula H-O- N \u003d N - O - H (2 points)

B. Decomposition: H 2 N 2 O 2 → H 2 O + N 2 O

Oxidation of air oxygen: 2H 2 N 2 O 2 + 3O 2 (WIT.) \u003d 2HNO 2 + 2HNO 3 Neutralization by alkali: H 2 N 2 O 2 + 2NAOH \u003d Na 2 N 2 O 2 + 2 H 2 O (3 points)

(other formulations of the response are allowed, not distorting its meaning)

Task 4. (8 points)

1. Copper (in color of the solution) and gold (non-solubility in nitric acid and the characteristic type of compact metal) (4 points: 2 points per item)

2. Dissolving in royal vodka (1 point)

Reaction equation:

AU + HNO 3 (conc.) + 4hCl (conc.) \u003d H + NO + 2H 2 O (2 points) (Options are also suitable for hydrochloric acid and chlorine, selenium acid, a mixture of nitric and hydrofluoric acids, etc. - to evaluate the full score.)

3. Any sensible method, for example: FE + CU (NO 3) 2 \u003d Cu + Fe (NO 3) 2 (1 point).

Task 5.. (10 points)

1. 2kmno 4 \u003d k 2 MNO 4 + MNO 2 + O 2 (2 points)

2. In a crystallizer with a current of oxygen, particles of potassium permanganate (1 point) 3. S + O 2 \u003d SO 2 (1 score )

2kmno 4 + 5 SO 2 + 2H 2 O \u003d K 2 SO 4 + 2MNSO 4 + 2H 2 SO 4 (2 point )

4. Sediment - MNO 2 manganese dioxide (2 points)

2kmno 4 + 3mnSO 4 + 2H 2 O \u003d 5mno 2 ↓ + K 2 SO 4 + 2H 2 SO 4 (2 point )

Final stage in Chemistry 2018-2019 uch. of the year
will be held on February 23 2019.

Basic

The beginning of the Olympics at 10:00 local time. List of playgrounds.

Winners and winners of the Olympiad last year are invited to participate in the Olympics, as well as winners and prize selection stages Olympiad of the current year (list of invited).

The duration of the Olympics is 4 astronomical hours.

On the day of the Olympiad

Registration at the place of entry begins at 9:30.

Participants necessarily need to have:

passport (or other document certifying)
A questionnaire for the final stage (formed from a personal account), signed by the parents and you
handle, pencil, ruler, calculator (not on the phone or tablet!)

I'm not listed? Or another problem?

Write a jury message in chemistry (http: // Website / VSESIB / → Feedback → Chemistry Jury) of the following content:
"I was not invited to the final stage, but I am a winner / prize of such a stage. My data: FULL NAME, ID in the Personal Account, Class, Status (Verification / Winner, Stage), region, settlement. Please include me in the list of invited participants. "

Having received a letter, we will make every effort to help you resolve the problem.

Prohibited!

The Olympics forbidden the use of phones and other means of communication and Internet access, any other electronic devices and gadgets, except for the usual or engineering calculator.

It is forbidden to use any books, cribs and other entries.

It is forbidden to use paper and reference information, including its own copies of Tables D.I. Mendeleev, solubility, etc.

Appeals

For participants of the Olympiad on the site in Magnitogorsk, a full-time appeal will be held on the day of the Olympics.

The time and place of full-time appeal in Novosibirsk will be reported additionally on the Olympiad website after the final stage.

For participants from other sites Correspondence appeal will be organized - instructions will be published on the Olympiad website after the final stage.

Summarizing

The results of the Olympics will be published as the works check. Work from all areas checks a single jury in Novosibirsk. Summing up and the definition of winners and medals will be carried out according to the unified rating of all participants after the end of full-time and correspondence appeal. Final results will be published no later than April 1, 2019.

Tasks

8th grade

2017-2018 academic year

Prepared:

chemistry teacher of the Semenov branch

MBOU "Kuibyshev School"

Apalkov Andrei Dmitrievich

Tasks

school stage All-Russian Olympiad schoolchildren in chemistry

8th grade

General (maximum) Number of points - 24

1. Consider the names of pure substances and mixtures: toothpaste, citric acid, ozone, steel, alcohol iodine solution, sea \u200b\u200bwater, iodine. (2 points)

2. Write chemical phenomena from the proposed range. Specify the signs that confirm your choice.

(2 points)

3. Three vessels of the same volume under normal conditions are filled with three different substances: nitrogen, chloride and water. Position the vessels in ascending order of the number of molecules in them. Justify the answer.(2 points)

4. Eggs shell consists mainly of calcium carbonate SASI 3. (4 points).

5 .

H. 2 Op. 2 O. 5 Alo. 2 Nah 2 O. 3 Co. 2 Na. 3 Ncfecl. 3 N. 2 TO 2 SiO. 3

(4 points)

6. The main vitamin contained in tea is Vitamin R. Its Formula - C 36 H. 28 O. 15 (4 points)

7. In the compound of iron with oxygen, the ratio of mass elements is 7: 3. Set the formula of this connection.(6 points)

Chemistry Olympiad School Stage Grade 8

Answers

Exercise 1. Determine the names of pure substances and mixtures: toothpaste, citric acid, ozone, steel, alcohol solution of iodine, sea water, iodine.

Clean substances: lemon Acid, Ozone, iodine

Mix: toothpaste, alcohol iodine solution, steel, sea water

Task 2. Remove chemical phenomena from the proposed number. Specify the signs that confirm your choice.

Paraffin melting; burning candles; Milk whisk; Baking pancakes; Education scale.

Chemical phenomena and their signs:

– The burning of the candle, as heat is highlighted, new substances are formed - soot and water.Or highlighting heat and light.

– Milk whisening, as the smell and precipitate appears.

– Baking pancakes because the color change occurs.

– Science formation, as a precipitate is formed.

Paraffin melting is not a chemical process.

0,25

Paraffin melting is not a chemical process, this is a physical phenomenon. Sign - change the aggregate state.

Maximum number of points

Task 3. Three vessels of the same volume under normal conditions are filled with three different substances: nitrogen, chloride and water. Position the vessels in ascending order of the number of molecules in them. Justify the answer.

The number of molecules is proportional to the amount of substance. Under equal conditions, equal volumes of gases contain equal amounts of substances, therefore, equal number of molecules. Under normal conditions, nitrogen and hydrogen are gases, and water liquid.

Consequently, the location will be carried out like this:

n (N. 2 ) \u003d N (HCl)< n(H 2 O)

Maximum number of points

Task 4.Eggs shell consists mainly of Calcium Calcium carbonate 3. Calculate how much calcium loses the chicken organism with each demolished egg if the mass of the shell is average equal to 10 g.(4 points)

M (sasso 3) \u003d 100g / mol. w. (Sa) \u003d 40%,

In 10g shell contains 4G calcium.

Answer. With each egg, the chicken loses 4 of calcium.

Maximum number of points

Task 5. The student received a task in which the names of substances it was necessary to make their chemical formulas. Performing this task, he did not leave the gaps between the formulas of substances, as a result of which he got a record:H. 2 Op. 2 O. 5 Alo. 2 Nah 2 O. 3 Co. 2 Na. 3 Ncfecl. 3 N. 2 TO 2 SiO. 3

Select the formula of individual substances from this record, emphasize these substances.

H. 2 O; P. 2 O. 5; Al; O. 2; Na; H. 2; O. 3; Co. 2; Na. 3 N; C; FECL 3; N. 2; TO 2 SiO. 3

Al; O. 2; Na; H. 2 ; C; N. 2 ;

Maximum number of points

Task 6. The main vitamin contained in tea is Vitamin R. Its Formula - C 36 H. 28 O. 15 . Determine the mass of one vitamin P molecule (in grams).

Mass of one caffeine molecule we find by the formulam.( C. 6 H. 12 O. 2 N. 4 )=
whereN. BUT - Number of Avogadro

M.( C. 6 H. 12 O. 2 N. 4 ) \u003d 6 · 12 + 12 · 1 + 4 · 14 \u003d 172 g / mol;

m.(C. 6 H. 12 O. 2 N. 4) \u003d 1 · 172: 6.02 · 10 23 \u003d 28.57 · 10 -23 (g)

Maximum number of points

Task 7.In the compound of iron with oxygen, the ratio of mass of elements is 7: 3. Set the formula of this connection.(6 points)

The mass fraction of the element in the compound is calculated by the formula

Answer: FE. 2 O. 3 .

Maximum number of points

The winner is from 14 points.

Conditions - from 8 to 14 points.

From March 30 to April 5 in Saransk at N.P. National Research Mordovia State University Ogareva passed the final stage of the All-Russian Olympiad of schoolchildren in chemistry. Students 9, 10 and 11 classes from 54 subjects arrived at the Olympics Russian Federation: Astrakhan region, Khabarovsk Territory, Yamalo-Nenets Autonomous Okrug, Moscow, St. Petersburg, Sverdlovsk, Novosibirsk regions and other regions of the country - only 245 schoolchildren.

March 30, the solemn opening of the Olympics took place. With a parting word for the participants of the Olympiad, the Deputy Chairman of the Government of the Republic of Mordovia, who oversees the issues of the social sphere, Galina Alekseevna Lotvnova , rector of the National Research Mordovian State University named after N.P. Ogareva Sergey Mikhailovich Vdovin and Dean of the Chemical Faculty of Moscow State University named after M.V. Lomonosov, Academician of the Russian Academy of Sciences, Chairman of the Jury of the Final Stage of the All-Russian Olympiad of Schoolchildren in Chemistry Valery Vasilyevich Lunin.

On March 31 and April 1, theoretical tours were held in the audiences of the National Research Mordovian State University named after N.P. Ogareva, and on April 2, a practical tour of the Olympics. On April 3, a demonstration took place at which schoolchildren got acquainted with their results and had the opportunity to discuss with members of the jury the course of solving problems and clarify their questions. On April 4, the participants of the Olympiad visited the industrial enterprises of Saranca.

On April 5, the closing ceremony took place. The participants and organizers of the Olympiad welcomed the head of the Republic of Mordovia Vladimir Dmitrievich Volkov. He also congratulated and presented gifts to participants and teachers, whose birthdays fell on the period of the final stage of the All-Russian Schoolchildren's Olympiad in Chemistry.

The jury of the Olympiad determined 19 of the strongest guys from Borovichi, Vologda, Dmitrovgrad, Izhevsk, Kazan, Lipetsk, Moscow, Nizhnekamsk, Novosibirsk, St. Pesleburg, Saransk and Tyumen who became winners. Another 91 schoolboy from different cities of Russia became the winner of the Olympics. Diplomas were awarded members of the jury Olga Valentinovna Arkhangelskaya and Vladimir Ilyich Termenin, as well as the rector of the National Research Mordovian State University named after N.P. Ogareva Sergey Mikhailovich Vdovin. Diplomas of the winners handed the dean of the Chemical Faculty of Moscow State University named after M.V. Lomonosov, Academician Rass Valery Vasilyevich Lunin.

It should be noted the absolute winner of the 9th grade Shishkin Alexei from G.Samara, who gained a total of 248 points out of 250, and the student of the 8th grade of Terlyakov Stanislav from Moscow became the prize among the participants from the 10th grade and the student of the 8th grade Davletbaeva Timur From Ufa, who became the winner among nine-graders.

From among the winners, the jury of the Olympiad selected the guys to participate in the 51st International Mendeleevskaya Olympiadwhich will be held on April 23-29 in Astana (Kazakhstan). Of the winners and the winners, teams for summer and winter fees to the international (world) Olympiad are also formed.

Winners of the Olympiad

Tasks and solutions

I Theoretical Tour

Tasks

Solutions

II Theoretical Tour

Tasks

Solutions

Experimental tour

Tasks and solutions

Brief photo report