To pass the final exams at school. It will need to be passed for admission to universities in the following areas: chemistry and chemical technology, medicine, construction, biotechnology and others. Against the general background, the exam is not very popular - only one student out of ten graduates chooses chemistry.
Read the general information about the exam and start preparing. The KIM USE 2019 version has some differences from last year: 1) a task was added to part 2 high level difficulty with a detailed answer, 2) for four questions, the difficulty level and the maximum primary score were revised (the maximum score did not change for the entire test), 3) for a clearer distribution of tasks by thematic blocks, the developers slightly changed their order in Part 1.
EGE assessment
Last year, in order to pass the exam in chemistry at least for a three, it was enough to score 37 primary points. They were given, for example, for the correctly completed first 15 tasks of the test.
How it will be in 2019 is still not known for sure: you need to wait for an official order from Rosobrnadzor on the compliance of primary and test scores. Most likely it will appear in December. Given that the maximum primary score for the entire test has remained the same, most likely will not change and minimum score. Let's take a look at these tables:
USE test structure
In 2019, the test consists of two parts, including 35 tasks.
- Part 1: 29 tasks (1-29) with a short answer (number or sequence of numbers);
- Part 2: 6 tasks (30–36) with a detailed answer, the complete solution of the tasks is recorded on the answer sheet 2.
Preparation for the exam
- Pass the USE tests online for free without registration and SMS. The presented tests are identical in their complexity and structure to the real exams held in the corresponding years.
- Download demo versions of the Unified State Examination in Chemistry, which will allow you to better prepare for the exam and make it easier to pass it. All proposed tests are designed and approved to prepare for USE Federal Institute of Pedagogical Measurements (FIPI). In the same FIPI, all official USE options.
The tasks that you will see, most likely, will not be found on the exam, but will be similar to the demo ones, on the same topic or simply with different numbers. - Check out the basic formulas for preparing for the exam, they will help refresh your memory before proceeding with the demo and test options.
General USE numbers
| Year | Min. USE score | Average score | Number of applicants | Did not pass, % | Qty 100 points |
Duration- exam length, min. |
| 2009 | 33 | |||||
| 2010 | 33 | 56,04 | 83 544 | 6,2 | 275 | 180 |
| 2011 | 32 | 57,75 | 77 806 | 8,6 | 331 | 160 |
| 2012 | 36 | 57,3 | 93 181 | 11 | 365 | 180 |
| 2013 | 36 | 67,8 | 93 802 | 7,3 | 3220 | 180 |
| 2014 | 36 | 55,3 | 180 | |||
| 2015 | 36 | 56,3 | 180 | |||
| 2016 | 36 | 180 | ||||
| 2017 | 36 | 180 | ||||
| 2018 |
Starts March 16th early period conducting the USE-2017 in chemistry. This optional subject cannot compete with history and social studies in terms of popularity. However, for admission to some higher institutions that are related to medicine, biotechnology and the oil industry, chemistry is indispensable. Therefore, for a small contingent of high school students and applicants, the USE in this subject will always be relevant. Our review is dedicated to them, highlighting the main aspects of the future state testing in chemistry.
the date of the
To begin with, let's figure out when it is worth waiting for the start of the state exam. In 2017, exams will take place between March and June.
- Early round - March 16.
- The main stage is June 2.
- Reserve - April 3, June 19 and 30.
Changes in the Unified State Examination in Chemistry 2017
The control and measuring material has changed significantly. The emphasis in the new KIMs is on the ability of the examinee to navigate well in all aspects of the school chemistry course.
- The number of tasks has decreased: 34 instead of the previous 40.
- The first part of the test work has been modified. Some questions are grouped into separate thematic blocks, tasks for correspondences have appeared.
- The maximum primary score has been reduced to 60 (was 64).
The structure of the control and measuring material
To understand what the new KIM looks like now, let's turn to the demo version of the Unified State Examination in Chemistry 2017.
The test subjects will have to break their heads over 34 tasks, which are divided into two unequal blocks. The first part contains 29 tasks, and the second - 5.
First block consists of basic questions. Basically, these are assignments for compliance. For example, question #5 has two columns. One consists of a list of formulas:
- A. NH4HCO3;
- B. KF;
- B. NO.
Second is a list of classes/groups of chemical elements:
- medium salt;
- acidic oxide;
- non-salt-forming oxide;
- salt is sour.
The examinee will be required to determine which group or class corresponds to which formula. For the second block of examination questions in chemistry 2017, FIPI prepared complicated tasks. They require not only an answer, but also a detailed description of the solution. These are questions 30-34.
The exam lasts exactly 210 minutes. You can use a calculator during the test. In addition, KIM has a periodic table, as well as a table of the solubility of salts / acids / bases in water and an electrochemical series of metal voltages.
Correct answers are recorded in a special examination form.
Criteria for assessing the exam in chemistry 2017
The number of tasks has decreased, which has introduced some confusion into the grading system. However, it is already known that the minimum score remained the same - 36. The maximum primary score decreased to 60. Points are awarded for correctly or partially correctly completed tasks.
- 1 point: questions 1 - 8, 12 - 16, 20 - 21, 27 - 29.
- 2 points: 9 – 11, 17 – 19, 22 – 26.
- 3 points: 30.
- 4 points: 31, 33 and 34.
- 5 points: 32.
You can only get these points for answers that fully meet all the criteria.
How to independently prepare for the exam in chemistry
Here is a list of web resources and teaching materials to help you prepare for your chemistry exam.
- Demo version. The easiest option. After studying the demo CMM, you will be aware of the structure of the future exam. And you can also solve the tasks presented in it. Fortunately, the demo contains the answers.
- Examer.ru. An online tutor consisting of a large number of training tasks.
- 4ege.ru. The largest portal dedicated to the Unified State Exam. In it you will find probes, collections of solved tests and various training work. In general, everything you need to saturate self-preparation for the exam in chemistry 2017 with preparatory material.
- Egeiria.ru. In a special section of this educational site, you can find the largest selection of educational literature, which is dedicated to the state exam in chemistry.
Afterword
So, we have analyzed the main aspects of the upcoming testing in chemistry. Now you know the exact date of the state exam, the structure of the KIM and the latest changes related to this subject. Moreover, the list of educational web portals and educational materials presented to your attention will help you start preparing for the exam right now. At the same time, most of the materials from sites dedicated to the exam in chemistry can be downloaded for free. So self-training will not cost you a pretty penny!
The 11th grade chemistry exam is by no means an easy one. It is required for admission to universities, which involve the continuation of chemical education. First of all, these are universities of a chemical-technological orientation, medical universities and classical universities. During the preparation for the Unified State Examination in Chemistry 2019, quite a lot of work needs to be done: to systematize and generalize knowledge, repeat the most important chemical concepts and practice solving tasks.
Changes in the USE 2018 in chemistry
- The total number of tasks has been increased from 34 to 35 due to the fact that one more task has been added in the second part. Now in part number 2, not 5, but 6 tasks. This was achieved in connection with the introduction of a task with a single context.
What do tasks 30 and 31 check? Ability to compose redox reactions and ion exchange reactions.
- The grading scale of some tasks in the first part has been changed.
it task number 9 an increased level of complexity, which is now estimated at a maximum of two points.
Task 21 the basic level of difficulty will be evaluated by one point. This is also a redox reaction in the format to establish a correspondence.
Task 26 – a basic level of complexity - assesses the assimilation of the experimental foundations of chemistry and general ideas about industrial methods for obtaining the most important substances. This task is also in the format of matching letters and numbers on the left and right sides. Estimated by one point.
Task number 30 a high level of complexity is in the second part of the exam and is focused on checking the assimilation of tasks on redox reactions. Scored with a maximum of 2 points.
Task 31st aimed at checking the assimilation of the topic "Ion Exchange Reactions" and is also evaluated by two points.
Structure of KIMs in chemistry
Exam option consists of 2 parts:
The tasks of the 1st part are arranged in ascending order of difficulty and are divided into content blocks and lines that are studied in the course of chemistry:
- "The structure of matter"
- "The structure of the atom"
- "Chemical reaction"
- "Not organic chemistry»
- "Organic chemistry"
- "Chemistry and Life"
- "Methods of cognition and the use of substances"
- "Calculations according to the equations of chemical reactions".
To prepare for the exam, it is very important to know the features that it has. Information about this is given on the FIPI website, where you can find demo version of the exam in chemistry and get acquainted with the structure of examination tasks.
Second part of the exam
This part causes the greatest difficulties for graduates.
Task number 30- a new task that appeared in 2018. A list of 5 substances is given. From this list, it is necessary to select those substances that will enter into a redox reaction. To do this, you need to find a pair of oxidizing agent and reducing agent. Then, if possible, determine the medium of the solution (acidic, alkaline, or neutral). Then you need to determine the reaction products in accordance with these starting materials. Next, you need to draw up an electronic balance of the reaction and, on its basis, already arrange the coefficients in the equation.
Task number 31- this is the task that was not in the exam in 2017. Here they check how eleventh-graders are able to compose ion exchange reactions that occur between electrolytes and necessarily in the direction of ion binding. The student chooses an ion exchange pair and shows his understanding of the course of this reaction. To do this, you need to write down the full and abbreviated ionic equation.
№32 This task is often referred to as a thought experiment task. There is a description of this or that experiment, and the student must draw up an equation for the chemical reactions of the ongoing processes. Evaluation scale - 4 points.
№33 - organic chemistry, where it is necessary to carry out a chain of transformations. When solving a chain, it is necessary to write down the structural formulas of substances that unambiguously reflect the order of connection of atoms in a molecule. It is permissible to write down the abbreviated structural formulas of substances such as ethane, acetylene.
Task number 34 is a computational problem that requires knowledge of the chemical properties of substances. It is necessary to draw up an equation of chemical reactions in the text, it is imperative to consider whether all the substance has reacted or part of it has not reacted with one of the reagents. Mathematical calculations that are necessary to find answers to the questions posed in the condition of the problem can be performed using a calculator, the periodic system. When solving, the graduate must show a logically justified answer, taking into account all the physical quantities that the condition of the problem gives. The maximum score for performance is 4 points. The Expert will deduct only 1 point if a calculation error is made.
Task #35 is the definition of the molecular and structural formula of organic matter. The sequence of actions of the graduate:
- Make a mathematical calculation, that is, the ratio of atoms in the composition of a particular organic substance.
- Compose a structural formula using the conditions given in the problem.
- Write an equation for a chemical reaction, in which it is necessary to use the structural formula of the substance.
The results of the Unified State Examination in Chemistry will help students who pass this subject to enter the chosen university and fulfill their dream of becoming a doctor or scientist, a chemist-technologist or a chemistry teacher.
The date of the exam is approved by the Ministry of Education of the Russian Federation and will be published in the next academic year.
More detailed advice on the exam "USE-2018. Chemistry" can be viewed here:
Table 1
Maximum amount points that an examinee can receive for completing the entire examination work of the OGE in chemistry (without a real experiment), - 34 points.
The results of the exam can be used when enrolling students in specialized classes high school. The benchmark for selection to profile classes can be an indicator, the lower limit of which corresponds to 23 points.
The scale for converting the primary score for the performance of the examination paper into a mark on a five-point scale (work with a real experiment, demo version 2)
table 2
The benchmark for selection in profile classes can be an indicator, the lower limit of which corresponds to 25 points.
The maximum number of points that an examinee can receive for completing the entire examination work (with a real experiment) is 38 points.
The system for assessing the performance of individual tasks and the examination work of the OGE 2018 in chemistry as a whole.
Checking students' answers to the tasks of part 1 is carried out by experts or using a computer. The correct performance of each of the tasks 1-15 is estimated at 1 point. The correct performance of each of the tasks 16-19 is estimated as a maximum of 2 points.
Tasks 16 and 17 are considered completed correctly if two answers are correctly selected in each of them. For an incomplete answer - one of the two answers is correctly named or three answers are named, of which two are correct - 1 point is given. The rest of the answers are considered incorrect and 0 points are scored.
Tasks 18 and 19 are considered completed correctly if three matches are correctly established. Partially correct is the answer in which two out of three matches are established; it is worth 1 point. The remaining options are considered incorrect answers and are scored 0 points.
Checking the tasks of part 2 (20–23) is carried out by the subject commission. When evaluating each of the three tasks, the expert, based on a comparison of the graduate's answer with the sample answer given in the evaluation criteria, identifies elements in the student's answer, each of which is estimated at 1 point. The maximum score for a correctly completed task: for tasks 20 and 21 - 3 points each; in model 1 for task 22 - 5 points; in model 2 for task 22 - 4 points, for task 23 - 5 points.
Tasks with a detailed answer can be completed by students in different ways. Therefore, the sample solutions given in the evaluation criteria should be considered only as one of the possible answers. This applies, first of all, to methods for solving computational problems.
Municipal budgetary educational institution
"Average comprehensive school No. 4 Shebekino, Belgorod Region"
Features of solving and evaluating tasks 30-35 USE in chemistry
Prepared by: Arnautova Natalya Zakharovna,
chemistry and biology teacher
MBOU "Secondary School No. 4 of Shebekino, Belgorod Region"
2017
Methods for evaluating tasks with a detailed answer (basic approaches to determining the criteria and assessment scale for completing tasks)
The basis of the methodology for evaluating tasks with a detailed answer is a number of general provisions. The most important among them are the following:
Verification and evaluation of tasks with a detailed answer is carried out only by independent examination based on the method of element-by-element analysis of the answers of the examinees.
The use of the element-by-element analysis method makes it necessary to ensure a clear correspondence between the statement of the task condition and the content elements being checked. The list of content elements checked by any task is consistent with the requirements of the standard for the level of preparation of secondary school graduates.
The criterion for evaluating the performance of a task by the method of element-by-element analysis is to establish the presence in the answers of the examined elements of the answer given
in the response model. However, another model of the answer proposed by the examinee can be accepted if it does not distort the essence of the chemical component of the task condition.
The task performance rating scale is set depending on the number of content elements included in the response model, and taking into account factors such as:
The level of complexity of the checked content;
A certain sequence of actions that should be carried out when performing a task;
Unambiguous interpretation of the conditions of the task and possible options for formulating the answer;
Compliance of the task conditions with the proposed evaluation criteria for individual elements of the content;
Approximately the same level of difficulty of each of the content elements tested by the task.
When developing assessment criteria, the features of the content elements of all five tasks with a detailed answer included in the examination paper are taken into account. It also takes into account the fact that the notes of the answers of the examinees can be either very general, streamlined and not specific, or too short.
and insufficiently substantiated. Close attention is paid to highlighting the elements of the answer, estimated at one point. This takes into account the inevitability of a gradual increase in the difficulty of obtaining each subsequent score.
for a well-formulated content element.
When compiling the assessment scale for calculation tasks (33 and 34), the possibility of various ways of solving them is taken into account, and therefore, the presence in the answer of the examinee of the main stages and results of completing the tasks indicated
in the evaluation criteria. Let us illustrate the methodology for evaluating tasks with a detailed answer using specific examples.
2017-2018 academic year
TasksJob level
Task 30
2016-2017
Tasks 30 are focused on testing the ability to determine the degree of oxidation of chemical elements, determine the oxidizing agent and reducing agent, predict the products of redox reactions, establish the formulas of substances omitted in the reaction scheme, draw up an electronic balance, and on its basis set the coefficients in the reaction equations.
The scale for assessing the performance of such tasks includes the following elements:
an electronic balance has been drawn up - 1 point;
the oxidizing agent and reducing agent are indicated - 1 point.
the formulas of the missing substances are determined and the coefficients are placed
in the redox reaction equation - 1 point.
Job example:
Using the electron balance method, write the equation for the reaction
Na 2 SO 3 + ... + KOH K 2 MnO 4 + ... + H 2 O
Determine the oxidizing agent and reducing agent.
Points
Possible answer
Mn +7 + ē → Mn +6
S +4 – 2ē → S +6
Sulfur in the +4 oxidation state (or sodium sulfite due to sulfur in the +4 oxidation state) is a reducing agent.
Manganese in oxidation state +7 (or potassium permanganate due to manganese
in the oxidation state +7) - an oxidizing agent.
Na 2 SO 3 + 2KMnO 4 + 2KOH \u003d Na 2 SO 4 + 2K 2 MnO 4 + H 2 O
The answer is correct and complete:
the degree of oxidation of elements, which are, respectively, an oxidizing agent and a reducing agent in the reaction, is determined;
the processes of oxidation and reduction are recorded, and on their basis an electronic (electron-ionic) balance is compiled;
substances missing in the reaction equation are determined, all coefficients are placed
Maximum score
When evaluating the answer of the examinee, it must be taken into account that there are no uniform requirements for the design of the answer to this task. As a result, the compilation of both electronic and electron-ionic balances is accepted as the correct answer, and the indication of the oxidizing agent and reducing agent can be done in any unambiguously understandable way. However, if the answer contains elements of the answer that are mutually exclusive in meaning, then they cannot be considered correct.
Tasks of the 2018 format
1. Task 30 (2 points)
To complete the task, use the following list of substances: potassium permanganate, hydrogen chloride, sodium chloride, sodium carbonate, potassium chloride. Permissible use aqueous solutions substances.
From the proposed list of substances, select substances between which a redox reaction is possible, and write down the equation for this reaction. Make an electronic balance, indicate the oxidizing agent and reducing agent.
Explanation.
Let's write the reaction equation:
Let's make an electronic balance:
Chlorine in the −1 oxidation state is a reducing agent. Manganese in the +7 oxidation state is an oxidizing agent.TOTAL 2 points
substances are selected, the equation of the redox reaction is written, all the coefficients are placed.
the processes of oxidation and reduction are recorded, and on their basis an electronic (electron-ionic) balance is compiled; which are, respectively, an oxidizing agent and a reducing agent in the reaction;
An error was made in only one of the above response elements
Errors were made in two of the above response elements
All elements of the answer are written incorrectly
Maximum score
Tasks of the 2018 format
1. Task 31 (2 points)
To complete the task, use the following list of substances: potassium permanganate, potassium bicarbonate, sodium sulfite, barium sulfate, potassium hydroxide. The use of aqueous solutions of substances is acceptable.
Explanation.
Possible answer:
2. Task 31
To complete the task, use the following list of substances: hydrogen chloride, silver (I) nitrate, potassium permanganate, water, nitric acid. The use of aqueous solutions of substances is acceptable.
From the proposed list of substances, select substances between which an ion exchange reaction is possible. Write down the molecular, full, and abbreviated ionic equations for this reaction.
Explanation.
Possible answer:
Task 32. Tasks of the 2018 format
In the condition of task 32, testing the knowledge of the genetic relationship of various classes of inorganic substances, a description of a specific chemical experiment is proposed, the course of which the examinees will have to illustrate by means of the equations of the corresponding chemical reactions. The task grading scale remains, as in 2016, equal to 4 points: each correctly written reaction equation is estimated at 1 point.
Job example:
Iron was dissolved in hot concentrated sulfuric acid. The resulting salt was treated with an excess of sodium hydroxide solution. The brown precipitate formed was filtered off and dried. The resulting substance was heated with iron.
Write the equations for the four described reactions.
Correct Answer Content and Grading Instructions(Other formulations of the answer are allowed that do not distort its meaning)Points
Possible answer
Four equations of the described reactions are written:
1) 2Fe + 6H 2 SO 4 
Fe 2 (SO 4) 3 + 3SO 2 + 6H 2 O
2) Fe 2 (SO 4 ) 3 + 6NaOH = 2Fe(OH) 3 + 3Na 2 SO 4
3) 2Fe(OH) 3 Fe 2 O 3 + 3H 2 O
4) Fe 2 O 3 + Fe = 3FeO
All reaction equations are written incorrectly
Maximum score
It should be noted that the absence of coefficients (at least one) in front of the formulas of substances in the reaction equations is considered an error. The score for such an equation is not set.
Task 33. Tasks of the 2018 format
Tasks 33 test the assimilation of knowledge about the relationship of organic substances and provide for the verification of five elements of the content: the correctness of writing the five reaction equations corresponding to the scheme - the "chain" of transformations. When writing reaction equations, examinees must use the structural formulas of organic substances. The presence of each checked content element in the response is estimated at 1 point. The maximum number of points for completing such tasks is 5.
Job example:
Write the reaction equations that can be used to carry out the following transformations:
When writing reaction equations, use the structural formulas of organic substances.
Correct Answer Content and Grading Instructionsother formulations of the answer are allowed that do not distort its meaning)
Points
Possible answer
Five reaction equations were written corresponding to the transformation scheme:
Correctly written five reaction equations
Correctly written four reaction equations
Three reaction equations are written correctly
Correctly written two reaction equations
Correctly written one reaction equation
All elements of the answer are written incorrectly
Maximum score
Note that in the answer of the examinee, it is permissible to use structural formulas of various types (expanded, abbreviated, skeletal), unambiguously reflecting the order of bonding of atoms and the relative position of substituents and functional groups
in an organic molecule.
Task 34. Tasks of the 2018 format
Tasks 34 are calculation tasks. Their implementation requires knowledge of the chemical properties of substances and involves the implementation of a certain set of actions to ensure that the correct answer is obtained. Among these actions are the following:
– compilation of equations of chemical reactions (according to the conditions of the problem) necessary to perform stoichiometric calculations;
– performing calculations necessary to find answers to the set
questions in the condition of the problem;
- formulating a logically justified answer to all the questions posed in the task condition (for example, to establish a molecular formula).
However, it should be borne in mind that not all of these actions must necessarily be present when solving any calculation problem, and in some cases some of them can be used repeatedly.
The maximum score for completing the task is 4 points. When checking, you should first of all pay attention to the logical validity of the actions performed, since some tasks can be solved in several ways. At the same time, in order to objectively evaluate the proposed method for solving the problem, it is necessary to check the correctness of the intermediate results that were used to obtain the answer.
Job example:
Determine the mass fractions (in%) of iron (II) sulfate and aluminum sulfide
in a mixture, if during the treatment of 25 g of this mixture with water, gas was released, which completely reacted with 960 g of a 5% solution of copper sulfate.
In your answer, 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).
Possible answer
The reaction equations are composed:
The amount of hydrogen sulfide substance was calculated:
The amount of substance and mass of aluminum sulfide and iron(II) sulfate were calculated:
The mass fractions of iron(II) sulfate and aluminum sulfide in the initial mixture were determined:
ω(FeSO 4 ) \u003d 10 / 25 \u003d 0.4, or 40%
ω (Al 2 S 3) \u003d 15 / 25 \u003d 0.6, or 6 0%
The answer is correct and complete:
in the answer, the reaction equations corresponding to the task condition are correctly written;
calculations are correctly made that use the necessary physical quantities specified in the task condition;
demonstrated a logically justified relationship of physical quantities, on the basis of which calculations are carried out;
in accordance with the condition of the assignment, the required physical quantity is determined
An error was made in only one of the above response elements
All elements of the answer are written incorrectly
Maximum score
When checking the answer, the examinee must take into account the fact that in the case when the answer contains an error in the calculations in one of the three elements (second, third or fourth), which led to an incorrect answer, the score for the task is reduced by only 1 point.
Task 35. Tasks of the 2018 format
Tasks 35 involve determining the molecular formula of a substance. The fulfillment of this task includes the following sequential operations: carrying out the calculations necessary to establish the molecular formula of an organic substance, writing the molecular formula of an organic substance, compiling a structural formula of a substance that unambiguously reflects the order of bonding of atoms in its molecule, writing a reaction equation that meets the condition of the task.
The grading scale for task 35 in part 2 of the examination paper will be 3 points.
Tasks 35 use a combination of verifiable content elements - calculations, on the basis of which they come to determine the molecular formula of a substance, draw up a general formula of a substance, and then determine, on its basis, the molecular and structural formula of a substance.
All these actions can be performed in a different sequence. In other words, the examinee can come to the answer in any logical way available to him. Therefore, when evaluating a task, the main attention is paid to the correctness of the chosen method for determining the molecular formula of a substance.
Job example:
When burning a sample of some organic compound weighing 14.8 g, 35.2 g of carbon dioxide and 18.0 g of water were obtained.
It is known that the relative hydrogen vapor density of this substance is 37. In the course of studying the chemical properties of this substance, it was found that when this substance interacts with copper (II) oxide, a ketone is formed.
Based on these conditions of the assignment:
1) make the calculations necessary to establish the molecular formula of organic matter (indicate the units of measurement of the required physical quantities);
write down the molecular formula of the original organic matter;
2) make a structural formula of this substance, which unambiguously reflects the order of bonding of atoms in its molecule;
3) write the equation for the reaction of this substance with copper(II) oxide using the structural formula of the substance.
Correct Answer Content and Grading Instructions(Other formulations of the answer are allowed that do not distort its meaning)
Points
Possible answer
The amount of substance of combustion products was found:
The general formula of a substance is C x H y O z
n (CO 2) \u003d 35.2 / 44 \u003d 0.8 mol; n (C) = 0.8 mol
n(H 2 O) \u003d 18.0 / 18 \u003d 1.0 mol; n(H) = 1.0 ∙ 2 = 2.0 mol
m (O) \u003d 14.8 - 0.8 ∙ 12 - 2 \u003d 3.2 g; n (O) \u003d 3.2 ⁄ 16 \u003d 0.2 mol
The molecular formula of the substance is determined:
x : y : z = 0.8: 2: 0.2 = 4: 10: 1
The simplest formula is C 4 H 10 O
M simple (C 4 H 10 O) = 74 g/mol
M ist (C x H y O z) \u003d 37 ∙ 2 \u003d 74 g / mol
The molecular formula of the starting substance is C 4 H 10 O
The structural formula of the substance has been compiled:
The equation for the reaction of a substance with copper oxide (II) is written:
The answer is correct and complete:
the calculations necessary to establish the molecular formula of a substance are correctly made; the molecular formula of the substance is written down;
the structural formula of an organic substance is written, which reflects the bond order and the mutual arrangement of substituents and functional groups in the molecule in accordance with the assignment condition;
the reaction equation is written, which is indicated in the task condition, using the structural formula of organic matter
An error was made in only one of the above response elements
Errors were made in two of the above response elements
Errors were made in three of the above response elements
All elements of the answer are written incorrectly
All elements of the answer are written incorrectly
Maximum score
TOTAL part 2
2+2+ 4+5+4 +3=20 points
Bibliography
1. Methodical materials for chairmen and members of subject commissions of subjects Russian Federation to check the performance of tasks with a detailed answer to the examination USE works 2017. Article "Methodological recommendations for assessing the performance of USE assignments with a detailed question." Moscow, 2017.
2. FIPI project of instrumentation USE materials 2018.
3. Demo versions, specifications, USE 2018 codifiers. FIPI website.
4. Certificate of planned changes in KIM 2018. FIPI website.
5. Website "I will solve the exam": chemistry, to the expert.
