Answers and solution - early version in chemistry 2017
To complete tasks 1-3, use the following row of chemical elements. The answer in tasks 1-3 is a sequence of numbers, under which the chemical elements in this row are indicated. 1) S 2) Na 3) Al 4) Si 5) Mg
1) Determine the atoms of which of the elements indicated in the series in the ground state contain one unpaired electron. Write down the numbers of the selected elements in the answer field
Let's write down the electronic configurations of these elements
S: 1s 2 2s 2 2p 6 3s 2 3p 4
Na: 1s 2 2s 2 2p 6 3s 1
Al:s 2 2s 2 2p 6 3s 2 3p 1
Si:1s 2 2s 2 2p 6 3s 2 3p 2
Mg: 1s 2 2s 2 2p 6 3s 2
We see that the elements Na and Al have one unpaired electron each
In a given transformation scheme X Y Cu CuCl CuI ⎯⎯→ ⎯⎯ 2 → substances X and Y are: 1) AgI 2) I2 3) Cl2 4) HCl 5) KI Write in the table the numbers of the selected substances under the corresponding letters
2 ) From the chemical elements indicated in the series, select three metal elements. Arrange the selected elements in ascending order of restorative properties. Write in the answer field the numbers of the selected elements in the desired sequence
Restorative properties increase from right to left in groups and from top to bottom in periods, therefore, we will arrange the three metal elements Na, Mg, Al Al, Mg, Na
3) From among the elements indicated in the row, select two elements that, in combination with oxygen, exhibit an oxidation state of +4. Write down the numbers of the selected elements in the answer field.
write possible compounds with oxygen
4) From the proposed list of substances, select two substances in which an ionic chemical bond is present.
1) KCl 2) KNO3 3) H3BO3 4) H2SO4 5) PCl3
5) Establish a correspondence between the formula of a substance and the class / group to which this substance belongs: for each position indicated by a letter, select the corresponding position indicated by a number.
6) From the proposed list of substances, select two substances, with each of which zinc interacts.
1) nitric acid (solution)
2) iron(II) hydroxide
3) magnesium sulfate (solution)
4) sodium hydroxide (solution)
5) aluminum chloride (solution)
3Zn + 8HNO3= 3Zn(NO3)2 + 4H2O + 2NO
Zn+ 2NaOH + 2H2O = Na2 + H2
7 ) From the proposed list of substances, select two oxides that react with water.
Write down the numbers of the selected substances in the answer field.
BaO+H2O= Ba(OH)2
8) A solution of substance Y was added to a test tube with a solution of salt X. As a result of the reaction, the formation of a white precipitate was observed. From the proposed list of substances, select substances X and Y that can enter into the described reaction.
1) hydrogen bromide
3) sodium nitrate
4) sulfur oxide (IV)
5) aluminum chloride
Write in the table the selected numbers under the corresponding letters.
AlCl3 + 3NH4OH = Al(OH)3+ 3NH4Cl
solution of substance NH3 -> NH3*H2O
9) In a given transformation scheme
Cu—X—CuCl2—Y——CuI
substances X and Y are:
Write in the table the numbers of the selected substances under the corresponding letters
2CuCl2 + 4KI = 2CuI + I2 + 2KCl
10) Establish a correspondence between the reaction equation and the oxidizing substance in this reaction: for each position indicated by a letter, select the corresponding position indicated by a number.
| REACTION EQUATION | OXIDIZER |
| A) H2 + 2Li = 2LiH | 1) H2 |
| B) N2H4 + H2 = 2NH3 | 2) N2 |
| C) N2O + H2 = N2 + H2O | 3) N2O |
| D) N2H4 + 2N2O = 3N2 + 2H2O | 4) N2H4 |
| 5) Li |
Answer: 1433
11) 1215
30) KI + KIO 3 + H 2 SO 4 = I 2 + K 2 SO 4 + H 2 O
| 2I -1 - 2e = I 2 0 | 5 | |
| 10 | ||
| 2I +5 + 10e =I 2 0 | 1 |
KI due to I -1 reducing agent
KIO 3 due to I +5 oxidant
5KI + KIO 3 + 3H 2 SO 4 = 3I 2 + 3K 2 SO 4 + 3H 2 O
1) 2Cu(NO 3) 2- → 2CuO + 4NO 2 + O 2
Early Unified State Examination in Chemistry 2017. Task 31
The gas obtained by calcining silver (I) nitrate was mixed with another gas obtained by the decomposition of potassium chlorate. The resulting mixture of gases was absorbed by water, and an acid was formed. Magnesium phosphide was treated with hydrochloric acid, and gas was released. This gas was carefully passed through a hot concentrated solution of the resulting acid. Write the equations for the five described reactions. In your answer, write the sum of the coefficients in all equations.
Early Unified State Examination in Chemistry 2017. Task 33
Potassium bicarbonate weighing 45 g was calcined to constant weight. The residue was dissolved in excess sulfuric acid. The resulting gas was passed through 200 g of a 5.6% potassium hydroxide solution. Determine the composition and mass of the formed salt, its mass fraction (%) in the solution. When solving, write down the reaction equations that are indicated in the condition of the problem, and give all the necessary calculations (indicate the units of measurement of the required physical quantities). In your answer, write down the sum of the molar mass (g / mol) of the formed salt, its mass (g) and its mass fraction (%, rounded up to a whole number) in the final solution. Ignore the solubility of gases in water.
Early Unified State Examination in Chemistry 2017. Task 34
When burning 12.24 g of organic matter of a non-cyclic structure, 20.16 l (n.o.) of carbon dioxide and 12.96 g of water were obtained. It is known that 1 mol of this organic substance attaches only 1 mol of water and this substance does not react with an ammonia solution of silver oxide. Based on the given conditions of the problem: 1) make the calculations necessary to establish the molecular formula of an organic substance. 2) make a molecular formula of organic matter. 3) make a structural formula of an organic substance, which unambiguously reflects the order of bonding of atoms in its molecule. 4) make an equation for the reaction of hydration of organic matter. In your answer, write down the molar mass (g / mol) of the original organic matter.
Tasks 33 and 34 with solutions.
No. 33: A mixture of copper and copper (II) oxide was treated with concentrated sulfuric acid. The volume of released gas was 4.48 liters. This formed a solution weighing 300 g with a mass fraction of salt 16%. Determine the mass fraction of copper (II) oxide in the initial mixture.
No. 34: A non-cyclic hydrocarbon was burned in oxygen, with the release of carbon dioxide weighing 70.4 g and water weighing 21.6 g. When interacting with HCl, this hydrocarbon adds chlorine to the primary carbon atom. Based on the given conditions of the problem: 1) make the calculations necessary to establish the molecular formula of an organic substance; 2) write down the molecular formula of the organic substance; 3) make a structural formula of the starting substance, which unambiguously reflects the order of bonding of atoms in its molecule; 4) write the reaction equation with HCl.
No. 34: When burning organic matter of a non-cyclic structure weighing 16.2 g, 26.88 liters (n.a.) of carbon dioxide, 16.2 g of water were released. 1 mole of a substance completely reacts with 1 mole of water. It is known that this substance does not react with OH. Based on the given conditions of the problem: 1) make the calculations necessary to establish the molecular formula of an organic substance; 2) write down the molecular formula of the organic substance; 3) make a structural formula of the starting substance, which unambiguously reflects the order of bonding of atoms in its molecule; 4) write the equation for the reaction of this substance with water.
Early versions of the exam in chemistry 2016-2015
| Chemistry | Download option |
| 2016 | variant ege 2016 |
| 2015 | variant ege 2015 |
Changes in KIM USE 2017 compared to 2016
Chemistry - significant changes. The structure of the examination paper has been optimized:
1. The structure of part 1 of the KIM has been fundamentally changed: tasks with a choice of one answer have been excluded; tasks are grouped into separate thematic blocks, each of which contains tasks of both basic and advanced levels of complexity.
2. Reduced the total number of tasks from 40 (in 2016) to 34.
3. The assessment scale has been changed (from 1 to 2 points) for completing tasks of the basic level of complexity, which test the assimilation of knowledge about the genetic relationship of inorganic and organic substances (9 and 17).
4. The maximum initial score for the performance of the work as a whole will be 60 points (instead of 64 points in 2016).
Structure of KIM USE 2017 in chemistry
Each version of the examination work is built according to a single plan: the work consists of two parts, including 34 tasks. Part 1 contains 29 tasks with a short answer, including 20 tasks of a basic level of complexity (in the version they are present under numbers: 1–9, 12–17, 20–21, 27–29) and 9 tasks of an increased level of complexity (their ordinal numbers: 10, 11, 18, 19, 22–26).
Part 2 contains 5 tasks of a high level of complexity, with a detailed answer. These are tasks numbered 30-34.
Total tasks - 34; of them according to the level of complexity: B - 20 P - 9; AT 5.
The maximum primary score for a job is 60.
The total time to complete the work is 210 minutes.
