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Ministry of Health of the Republic of Uzbekistan

Ministry of Higher and Special Education of the Republic of Uzbekistan

WORKSHOP IN GENERAL CHEMISTRY

Tashkent - 2004

Reviewers:

Professor of the Department of Bioorganic and Biological Chemistry II TashGosMI Kasymova S.S.

Assoc. Department of General Chemistry, TashPMI Arifjanov S.Z.

A.D. Dzhuraev, N.T. Alimkhodzhaeva and others.

Workshop on General Chemistry: Textbook for Medical Students

The guide contains the content of laboratory classes in the course of general chemistry for students of medical institutes. For each lesson, the goals and objectives of this topic are given, the questions considered in the lesson, the significance of the topic under study, a block of information on this topic, training tasks with standards for their solution, situational tasks, questions, tasks and tests to identify the assimilation of this topic, the methodology for conducting laboratory works and tasks for independent solution.

The workshop was compiled in accordance with the new program of teaching the course "General Chemistry" for students of medical institutes.

FOREWORD

Chemistry is one of the fundamental general theoretical disciplines. It is closely connected with other natural sciences: biology, geography, physics. Many sections of modern chemical science arose at the intersection of physical chemistry, biochemistry, geochemistry, etc. In modern chemistry, many independent sections have emerged, the most important of which are inorganic chemistry, organic chemistry, analytical chemistry, polymer chemistry, physical chemistry, etc. General chemistry considers basic chemical concepts, as well as the most important patterns associated with chemical transformations. General chemistry includes the foundations from various sections of modern science: physical chemistry, chemical kinetics, electrochemistry, structural chemistry, etc. The most important functions of general chemistry include, firstly, the creation of a theoretical basis for the successful mastery of special disciplines, and secondly, the development in the process of teaching modern forms of theoretical thinking, which is extremely relevant, since among the requirements for a modern specialist, the need for both a theoretical view of the objects and phenomena being studied, and the ability to think independently, the ability to think from the standpoint of science, to go beyond the framework of a narrow specialty in solving complex problems and the acquisition of practical skills in the analysis of biological objects.

The role of chemistry in the system of medical education is quite large. The study of such important areas in medicine as molecular biology, genetics, pharmacology, quantum biochemistry, etc. is impossible without knowledge of the theory of the structure of matter and the formation of chemical bonds, chemical thermodynamics, the mechanism of chemical reactions and other issues.

One of the sections of general chemistry according to the program for medical schools is bioinorganic chemistry, which arose on the basis of inorganic chemistry, biochemistry, biology, biogeochemistry.

Bioinorganic chemistry studies the composition, structure, transformation of biomolecules containing metal ions, their modeling. This science explores the mechanisms of participation of inorganic ions in the course of biochemical processes.

Using the achievements of bioinorganic chemistry, it is possible to explain the behavior of chemical elements in biological systems.

And today, the statement of the great Russian scientist M.V. Lomonosov is very true: "A physician cannot be perfect without a satisfied knowledge of chemistry."

INTRODUCTION

This study guide has been compiled to help medical students studying general chemistry. It is necessary for independent preparation of students for laboratory and practical classes.

The purpose of this manual is to develop, on the basis of modern achievements, students' skills in qualitative and quantitative prediction of the products of the transformation of substances in a living organism based on the study of typical chemical reactions, as well as to systematize knowledge of the most important theoretical generalizations of chemistry; to teach how to apply this knowledge to phenomena occurring in a living organism in normal and pathological conditions.

As a result of mastering the course of bioinorganic chemistry:

The student must know:

The doctrine of solutions, on the basis of which to evaluate the properties of non-electrolytes and electrolytes to predict the influence of the environment on the course of biochemical reactions (processes); ways of expressing the compositions of solutions; be guided by the protolytic theory of acids and bases as the basis for considering acid-base interactions in living organisms;

Basic concepts and laws related to the thermodynamics of chemical processes that determine the direction and depth of biochemical reactions;

Basic laws of chemical kinetics as applied to biological systems;

The main patterns of the course of redox processes and precipitation processes to predict the likely products of the transformation of substances in biochemical systems and drugs used in medicine;

The main provisions of the theory of the structure and reactivity of complex compounds to predict the formation of the most probable products in living organisms between metal ions and bioligands for their use in medicine;

Typical properties of compounds of s, p, d elements in connection with their location in the periodic system of elements of D.I. Mendeleev for predicting the transformation of chemical elements in biological systems.

Types of chemical reactions. Exothermic and endothermic reactions

As a result of mastering the course of bioinorganic chemistry

The student must be able:

work independently with educational and reference literature, use their data to solve typical problems as applied to biological systems;

choose the conditions for conducting reactions to obtain specific compounds;

predict the possibility of chemical reactions and draw up equations for the reactions of their occurrence;

own modern techniques of laboratory chemical work for qualitative and quantitative analysis of medical preparations and biological objects;

Compose abstracts for ongoing analyzes and scientifically substantiate the experimental data obtained in application to medical practice.

The guide provides the goals and objectives of this topic, the issues considered in the lesson, the significance of the topic under study, a block of information on this topic, training tasks with standards for their solution, which are an indicative basis for action when applying theoretical provisions to specific tasks, as well as situational tasks, questions, tasks and tests to identify the assimilation of this topic, the methodology for conducting laboratory work and tasks for independent solution.

The basis of this guide includes works that have been used for a number of years in the educational process in I Tashkent State Medical Institute and Tashkent State Medical Institute when studying the course of general chemistry. The workshop was compiled in accordance with the program of teaching the course, "general chemistry" for students of medical institutes.

When compiling the manual, special attention was paid to the medical bias of teaching general chemistry.

Rules for working in a chemical laboratory

The technique of modern chemical research is complex and varied. The initial stage of their implementation is laboratory and practical classes in general chemistry, where elementary skills are acquired in working in a chemical laboratory with chemical equipment, utensils, etc., to perform simple experiments.

Each student working in a chemical laboratory must strictly observe the following work rules:

I. Each worker in the laboratory is assigned a workplace that cannot be cluttered with unnecessary items, put briefcases, books, bundles, etc. on the table. The workplace should be kept neat and tidy.

2. Before each laboratory work, the theoretical material related to it should be studied, experiments should be started only after carefully reading the instructions (manual) and clarifying all incomprehensible questions. All laboratory work is carried out individually.

3. Carefully use reagents, gas, water, electricity. For experiments, take the minimum amount of substance. Reagents that have not been used or taken in excess must not be returned to the vials. The remains of rare, expensive and poisonous compounds should be poured into special vessels kept by the laboratory assistant.

4. All bottles with reagents and solutions should be immediately closed with stoppers after use, which must not be confused. It is forbidden to carry reagents of common use to their place. It is not recommended to put bottles with reagents on books and notebooks.

5. It is necessary to work in the laboratory in dressing gowns, it is strictly forbidden to eat, it is not allowed to smoke and talk loudly.

6. Upon completion of work, it is necessary to wash the used dishes, carefully clean the workplace, turn off the gas, water, electricity.

7. All data of laboratory work performed should be recorded in a laboratory journal. It contains: the theoretical material necessary for the performance of this work, the methodology for performing laboratory work, observations, reaction equations, calculations, answers to questions, problem solving, scientifically based analysis results, conclusions made on the basis of the study. The entry in the journal should be accurate and drawn up in such a way that a chemist who is not familiar with this work, after reading it, can clearly imagine how the experiments were carried out, what was observed in them, what conclusions the experimenter came to. The laboratory journal must be completed during the analysis as it is performed. No drafts are allowed. It is strictly forbidden to gloss over or alter the numbers in the protocol of experiments.

Safety rules for working in a chemical laboratory

When performing laboratory work in a chemical laboratory, safety regulations must be observed

Laboratory work is usually carried out at the chemistry table. The table must be clean. Before starting laboratory work, it is necessary to make sure that all reagents and utensils are available.

The experiment should be carried out strictly in the sequence indicated in its description. When heating, do not hold test tubes and flasks with the opening towards yourself or someone working nearby; do not bend over the opening of the vessel in which the reaction takes place.

Work with flammable substances should be carried out away from fire.

When igniting benzene, ether, gasoline, it is impossible to extinguish the fire with water, it is necessary to cover the fire with sand.

Work with caustic, poisonous and odorous substances in a fume hood. Pour concentrated acids and alkalis under draft. In no case should their remains be poured into the sink, but into specially designated bottles. Under draft, carry out all reactions accompanied by the release of toxic gases or vapours.

Place hot appliances and dishes on special stands.

If acid gets on the face and hands, wash it off with a strong stream of water from the tap, and then rinse the affected area with a diluted solution of tea soda; if alkali comes into contact with the skin, rinse thoroughly with water, and then with a dilute solution of acetic acid.

In case of burns with hot objects, close the burned area with gauze soaked in a weak solution of potassium permanganate. In case of glass cuts, the blood should be washed with a weak solution of potassium permanganate or alcohol, the wound should be lubricated with an iodine solution, bandaged.

Remember that salts containing mercury, arsenic, barium, lead are poisonous; Wash your hands thoroughly after using them.

When testing gas by smell, hold the test tube in the left hand so that the hole is below the level of the nose, with the right hand direct a weak stream of air towards you.

It must be well remembered that in a chemical laboratory special care, conscientiousness and accuracy are required when performing laboratory work. This will ensure success at work.

Each student is allowed to conduct laboratory work only after studying the safety rules when working in a chemical laboratory.

FROMways of expressing the concentration of solutions in the systemSI.

Purpose of the lesson. To learn how to carry out quantitative calculations for the preparation of solutions of various concentrations necessary for the analysis of biological objects. To learn experimentally, to prepare solutions of a given concentration used in medical practice.

The significance of the topic under study. Liquid solutions, primarily aqueous solutions, are of great importance in biology and medicine. They are the internal environment of living organisms, where vital processes take place, primarily metabolism. Biological fluids: blood plasma, lymph, gastric juice, urine, etc. - are complex mixtures of proteins, lipids, carbohydrates, salts dissolved in water. The solubility of drugs in water is taken into account when using them for treatment. Solutions of drugs in medical practice are always used with a numerical expression of their composition. Therefore, knowledge of the units of measurement of the concentration of solutions is necessary for the doctor. Carrying out quantitative calculations for the preparation of solutions of a given concentration is very important in medical practice, since in clinical, sanitary and hygienic and other analyzes, drugs are used in the form of solutions of a known concentration.

Initial level of knowledge:

1. Solubility of substances in water;

2. Concepts: solute, solvent, solution;

3. Chemical theory of the formation of solutions by D.I. Mendeleev;

4. Concentration of solutions;

5. Solutions saturated, unsaturated, supersaturated, concentrated, diluted.

N.L. Glinka. General chemistry. L., 1976, p. 213.

S.S. Olenin, G.N. Fadeev. Inorganic chemistry. M., 1979, p. 107.

A.V. Babkov, G.N. Gorshkova, A.M. Kononov. Workshop on general chemistry with elements of quantitative analysis. M., 1978, p. 32.

The lesson will cover the following questions:

Methods for expressing the concentration of solutions:

I.1. mass fraction of the component - u(X), u(X)%:

I.2. mole fraction -N(X); volume fraction - f(X);

I.3. molar concentration-c(X);

I.4. molal concentration-in(X);

I.5. molar concentration of equivalent c(feq(x)x) = c(

I. 6. equivalence factor fequiv(x) = (

I.7. equivalent f equiv(x)х = (

I.8. molar mass equivalent of M f eq (x) x = M (

I.9. the amount of substance equivalent n (f eq (x) x) = n (

I.10. solution titer - t(x)

Solving problems on the topic.

3. Laboratory work

Binformation lock

Basic terms and units of measurement concentration of solutions in the SI system.

Solutions are homogeneous systems consisting of two or more components and products of their interaction. . The most significant are solutions of solid, liquid and gaseous substances in liquid solvents, usually in water.

A certain amount of a solute contained in a certain weight amount or a certain volume of a solution or solvent is called the concentration of the solution.

In connection with the introduction of the international system of units (SI), there have been some changes in the ways of expressing the composition of the solution. In this system, the basic unit of mass, as you know, is the kilogram (kg), gram (g), the unit of volume is liter (l), milliliter (ml), the unit of the amount of substance is the mole.

The amount of substance of the system-n(X) - a dimensional physical quantity characterized by the number of structural particles contained in the system - atoms, molecules, ions, electrons, etc. The unit of measurement of the amount of a substance is a mole. This is the amount of a substance containing as many real or conditional particles as there are atoms in 0.012 kg of a carbon isotope with a mass of 12. For example: n (HCl) \u003d 2 mol or 2000 mmol; n(H+)= 3?10-3 mol; n(Mg2+) = 0.03 mol or 30 mmol

Molar mass M(X) - the mass of one mole of the substance of the system is the ratio of the mass of the substance to its quantity. Units of measurement - kg/mol, g/mol.

M(X)=, g/mol

M(X)- molar mass of substance X of the system;

m(X)- mass of substance X of the system;

n(X)- the amount of substance X of the system.

For example:

M(Cl2)=70.916 g/mol; M(Ca2+)=40.08 g/mol; M(NaCl)=58.50 g/mol.

Mass fraction of the component -sch(X),sch%(X) - a relative value representing the ratio of the mass of a given component contained in a system (solution) to the total mass of this system (solution) (instead of the concept of percentage concentration). It is expressed in fractions of a unit and as a percentage (%).

; ;

For example: sch %(NaCl)=20%; sch %(HCl)=37%.

Molar(molar) fraction of the component -N ( X ) - a relative value equal to the ratio of the amount of the substance of the component contained in the given system (solution) to the total amount of the substance of the system (solution).

The molar fraction is often denoted by the letter N(X).

Volume fraction of the component -f (X) - relative value equal to the ratio of the volume of the component contained in the system (solution) to the total volume of the system (solution).

Molar concentration -c(X) the ratio of the amount of substance (X) in the system (solution) to the volume of this system (solution).

With (X)= =, mol/l

With (NSl)= 0.1 mol/l; c(Cu2+)= 0.2378 mol/l

Molar concentration -b(x) - the ratio of the amount of substance (X) contained in the system (solution) to the mass of the solvent.

in(x) = mol/kg

For example

c(ncl)= 0.1 mol/kg.

Equivalence factor- f eq(X)= - a dimensionless quantity denoting what proportion of a real particle of a substance (X) is equivalent to one hydrogen ion in an acid-base reaction or one electron in a redox reaction. The equivalence factor is calculated based on the stoichiometry of the given reaction. For example:

NaOH+H2SO4=Na2SO4+H2O; f equiv(NaOH)=1, fequiv(H2SO4 )=

Equivalent -f eq(X) - dimensionless value - a real or conditional particle of a substance (X), which in a given acid-base reaction combines with one mole of hydrogen or is in some way equivalent to it or equivalent to one electron in redox reactions.

Molar mass equivalent-M( f eq (x)) = M the mass of one mole equivalent of a substance, equal to the product of the equivalence factor by the molar mass of the substance:

M (f equiv (x) x) \u003d M () \u003d f equiv (x) MM (x), g / mol

M (H2SO4) \u003d M (H2SO4) \u003d 49.0 g / mol

Toamount of substance equivalent

n ( f eq( x ) x ) = n (

- the amount of a substance in which the particles are equivalents:

n(= , mol; n(Ca2+)= 0.5 mol

Molar equivalent concentration

with( f eq(x)x)=c(

- the ratio of the amount of an equivalent substance in a system (solution) to the volume of this system (solution):

with(feq (x) x) \u003d c= =mol/l = 0.1 mol/l

Solution titer-t ( x )- mass of substance (X) contained in I ml of solution:

t (x) = - ,g/ml

t(HCl)= 0.003278 g/ml

Learning tasks and standards for their solution.

m(H2 O)=200.00g

m(CuSO4 5H2O) \u003d 50.00 g

M(CuSO4)=342.16g/mol

M(CuSO4 5H2O) \u003d 25000 g / mol

sch%(CuSO4 5H2O) \u003d?

sch% (CuSO4)=?

Decision reference

Find the mass of the resulting solution:

m(p- p)= m(in-in)+m(H2 O)=50.00 g+200, C g=250.00 g.

m(p-p)=250.00G.

Find the mass fraction of CuSO4 5H2O in solution:

sch% (CuSO4 5H2O) =

sch%( CuSO4 5H2O) =

We find the mass of anhydrous salt in 50.00 g of copper sulfate. The molar mass of CuSO4 5H2O is 250.00 g/mol, the molar mass of CuSO4 is 160.00 g/mol. I mol CuSO4 5Н2О contains I mol CuSO4. Thus, I mol x 250.00 g / mol \u003d 250.00 g CuSO4 5H2O contains I mol x 160.00 g / mol \u003d 342.16 g CuSO4:

in 250.00 g CuSO4 5H2O -160.00 g CuSO4

We make up the proportion: 250.00: 160.00 \u003d 50.00: x.

Solving it, we find the mass of anhydrous copper sulfate:

Find the mass fraction of anhydrous salt:

sch%( CuSO4)=

sch%( CuSO4)=

sch%( CuSO4 5H2O) = 20%;sch%( CuSO4) = 25,60%

Task #2 How many ml of a 96% (mass) solution of H2SO4 (c = 1.84 g / ml) should be taken to prepare 2 liters of a 0.1000 mol / l solution of H2SO4?

sch%(H2SO4)=96%;

With=1.84g/ml

V(p- p)=2.00l

with(H2 SO4)=0.1000 mol/l

M(H2SO4)=98.0g/mol

V(H2SO4)=?

Decision reference

1. Find the mass of H2SO4 containing 2 liters of a solution of a molar concentration of 0.1000 mol / l. It is known that

with(H2 SO4)= , then

m(H2SO4)= c(H2 SO4) M(H2SO4) V(p- p)

m(H2SO4)=0,1000 M98 M2,00 G

m(H2SO4)=19.60g.

2. Find the mass of a 96% (mass) solution of H2SO4 containing 19.60 g of H2SO4

sch%(H2SO4)=

m(p- p)=

3. We find the volume of the H2SO4 solution, knowing its density.

m(p- p)= V(p- p) MWith (p- p); then V(p- p)=

V(p- p)= 20.42/1.84=11.10ml

V(H2 SO4)= 11.10ml

Task number 3. Determine the molar concentration of 200 g of an antiseptic agent of 2.0% (wt.) Alcoholic solution of brilliant green ("brilliant green"). M (bril. green) \u003d 492 g / mol; (c=0.80g/ml).

sch%(in-va)=2.0%

with(solution)=0.80g/ml

M (in-in) \u003d 492.0 g / mol

with (in-in) \u003d?

Decision standard.

Find the mass of the substance in 200.00 g of brilliant green solution.

Find the volume of the alcohol solution:

V(p-p)=V(p-p)=

We find the molar concentration c (in-in) in the solution:

c (in-in) \u003dc (in-in) \u003d

s (in-in) \u003d 0.06500 mol / l

Task number 4. The titer of NaOH solution, widely used in drug analysis, is 0.003600 g/ml. When reacted with sulfuric acid, it forms an acid salt. What is the molar concentration of the equivalent of the solution in its reaction with sulfuric acid; mass fraction of NaOH (%) in solution? Calculate the amount of NaOH required to prepare 1 liter of such a solution.

t(NaOH) =0.003800 g/ml

V(p- p)=1.00 l

M(NaOH)=40.0 g/mol

With (p- p)=1.0g/ml

With(NaOH)=?m(NaOH)=?

sch%(NaOH)=?

Decision standard.

The equation of the ongoing reaction:

H2SO4 + NaOH = Na HSO4 + H2O

feq(H2SO4)=1; feq(NaOH)=1.

Thus, in this case, we should speak about the molar concentration of the NaOH solution.

Find the mass of NaOH required to prepare 1000 ml of solution:

t(NaOH)=

m(NaOH)= t(NaOH)V(p-p)

m(NaOH)=0.003800 1000gml/ml=3.8g

Find the molar concentration of the solution:

With(NaOH)=

With(NaOH)=\u003d 0.0950 mol / l

Find the mass of 1 liter of solution:

m(solution)=1000ml 1 g/ml=1000g

4. Find the mass fraction of NaOH (%) in the solution:

sch%(NaOH)=

sch%(NaOH)=

Answer: with(NaOH)=0.0950mol/l

sch%(NaOH)= 0,38%

m(NaOH)=3.8g

situational tasks.

1. How many ml of a 30% (wt.) solution of HCl (c = 1.152 g / ml) should be taken to prepare 1 liter of a 3% (wt.) solution of it, used orally with insufficient acidity of gastric juice? What is the molar concentration and titer of the resulting solution. (Standardization of the solution is performed by NaOH).

Answer: V(HCl)=84.60 ml; c(HCl)=0.8219mol/l.

2. Calculate the molar concentration of saline NaCl. How much water should be added to 200 ml of 20% NaCl solution (=1.012 g/ml) to prepare 5 liters of saline?

Answer: c (NaCl) = 0.000147 mol/l

V(H2O) = 4504 ml

3. Nicotinic acid - vitamin PP - plays a significant role in the life of the body, being a prostatic group of a number of enzymes. Its deficiency leads to the development of pellagra in humans. Ampoules for medicinal purposes contain 1 ml of 0.1% (wt.) nicotinic acid. Determine the molar concentration of the equivalent and the titer of this solution

Standardization is carried out by NaOH solution.

Answer: t(H-R)=0.00100g/ml

c(H-R)=0.08130 mol/l

Test questions

Calculate the H2SO4 equivalence factor in this reaction

H2S04 + KOH = KHS04 + H2O

a) 1b) 2c) 1/2d) 1/3e) 3

The titer of NaOH solution is 0.03600 g/ml. Find the molar concentration of this solution.

a) 9 mol/l b) 0.9 mol/l c) 0.09 mol/l d) 0.014 mol/l e) 1.14 mol/l

What solution does the value of Vsolubility refer to< V кристаллизация.

a) saturated solution c) supersaturated solution

b) unsaturated solution d) dilute solution

e) concentrated solution

Find the mass fraction (%) of glucose in a solution containing 280 g of water and 40 g of glucose

a) 24.6% b) 12.5% ​​c) 40% d) 8% e) 15%

Determine the H2SO4 equivalence factor in this reaction

Mg(OH)2+2H2SO4=Mg(HSO4)2+2H2O

a) 2 b) 1 c) 1/2 d) 4 e) 3

The molar concentration of a substance in a solution is determined by:

a) the molar number of the substance in 1 liter of solution

b) the molar number of the substance in 1 ml of solution

c) the molar number of a substance in 1 kg of solution

d) the molar number of a substance in 1 g of solution

How many types of aggregate states of a solution are there?

a) 2b) 3c) 1 d) 4

9. Specify the concentrated NaOH solution:

a) 0.36% b) 0.20% c) 0.40% d) 36%

Find the molar concentration of saline NaCl.

w% (NaCl)=0.85%

a) 1 mol/l b) 0.14 mol/l c) 1.5 mol/l e) 9.31 mol/l d) 10 mol/l

LABORATORY WORK 1

1.1 Preparation of solutions of a given concentration

There are three methods for preparing a solution of a given concentration:

dilution of a more concentrated solution

the use of a certain sample of solids.

fixed channel method.

1. Preparation of a 0.1 molar solution of sulfuric acid by diluting more than concentrated solution:

Pour a solution of sulfuric acid into a beaker and determine the density of this solution with a hydrometer. Then, using the table, determine the mass fraction of sulfuric acid in this solution.

Measure the required volume of sulfuric acid in a small beaker and carefully, using a funnel, pour it into a 100 ml volumetric flask half-filled with distilled water. Cool the mixture in a volumetric flask to room temperature and carefully add water to the volumetric mark. Close the volumetric flask tightly with a lid and, after thorough mixing, hand over to the laboratory assistant.

Solution preparation by the method of dissolving a certain sample of a solid substance:

Find out from the teacher the solution of what concentration you need to prepare. Then make a calculation: how many grams of salt you need to dissolve to obtain a solution with a given concentration and weigh the required amount of salt with an accuracy of 0.01 g.

Stir the solution with a glass rod with a rubber tip until the salt is completely dissolved. If an increase or decrease in temperature is observed during dissolution, wait until the temperature of the solution reaches room temperature.

Pour the resulting solution into a dry cylinder and measure the density of the resulting solution with a hydrometer. According to the table, determine the mass fraction of the solute corresponding to the density.

% error = (shteor-practic) 100 / shteor

ATvetitrimetric analysis

Purpose of the lesson: To get acquainted with the basics of titrimetric analysis, as one of the quantitative research methods used in medical practice for the analysis of biological objects and drugs, as well as for the sanitary assessment of the environment.

The significance of the topic under study. The method of titrimetric (volume) analysis is widely used in biomedical research to determine the quantitative composition of biological objects, medicinal and pharmacological preparations.

Without knowledge of the composition of various environments of living organisms, neither understanding of the essence of the processes occurring in them, nor the development of scientifically based methods of treatment is possible. Diagnosis of many diseases is based on comparing the results of tests for a given patient with the normal content of certain components in the blood, urine, gastric juice, other body fluids and tissues. Therefore, medical professionals, especially doctors, need to know the basic principles and methods of titrimetric analysis.

Initial level of knowledge.

Fundamentals of the theory of electrolytic dissociation of acids, bases, salts;

Types of chemical reactions (in molecular and ionic form);

Methods for expressing the concentration of solutions.

Educational material for self-study.

1. V.N. Alekseev. Quantitative analysis. M., 1972, p.193.

2. A.A. Seleznev. Analytical chemistry. M., 1973, p. 164.

I.K.Tsitovich. Analytical chemistry course. M., 1985. str. 212.

The lesson will cover the following questions:

1. Problems of analytical chemistry

2. Essence of methods of titrimetric analysis

2.1. Basic concepts: solutions used in titrimetric analysis

2.2. Equivalence point

2.3. Requirements for reactions used in titrimetric analysis

2.4. Measuring utensils: burettes, pipettes, volumetric flasks, volumetric cylinders.

2.5. Titration technique.

2.6. Calculations in the titrimetric method

2.7. Classification of titrimetric analysis methods

Application of methods of titrimetric analysis in medical practice.

4. Laboratory work

Information block

Analytical chemistry is a science that studies methods for determining the qualitative and quantitative chemical composition of substances or their mixtures. It is divided into qualitative and quantitative analysis. Qualitative analysis methods determine which chemical elements, atoms, ions or molecules the analyzed substance consists of. Quantitative analysis methods establish the quantitative ratios of the constituent components of a given test compound.

Quantitative analysis is carried out by various methods. Chemical methods are widely used, in which the amount of a substance is determined by the amount of reagent used for titration, by the amount of sediment, etc. The most important are three methods: weight, titrimetric (volume) and colorimetric.

The essence of weight analysis lies in the fact that the component of the analyte is completely isolated from the solution in the form of a precipitate, the latter is collected on a filter, dried, calcined in a crucible and weighed. Knowing the weight of the precipitate obtained, the content of the desired component is determined by the chemical formula of the latter.

In titrimetric (volume) analysis, the quantitative determination of the constituent components of the analyte is carried out by accurately measuring the volume of a reagent of known concentration that enters into a chemical reaction with the analyte.

The colorimetric method of analysis is based on comparing the intensity of the color of the test solution with the color of the solution, the concentration of which is precisely known.

In clinical analysis, titrimetric analysis methods are most widely used, since they do not require much time, are easy to perform, and can be used to obtain fairly accurate results.

The method of titrimetric analysis is based on an accurate measurement of the volume of the reagent consumed in the reaction with the analyte X. The process of adding one solution in the burette to another solution to determine the concentration of one of them (at a known concentration of the other) is called titration. The term titration is derived from the word titer, which means the content of the reagent in grams in 1 ml of solution.

A reagent solution of exactly known concentration is called a working titrated or standard solution. A solution with a precisely known concentration can be obtained by dissolving an exact sample of a substance in a known volume of a solution or by establishing the concentration from another solution, the concentration of which is known in advance. In the first case, a solution with a prepared titer is obtained, in the second - with a fixed titer.

For the preparation of a solution with a given concentration, only such substances are suitable that can be obtained in a very pure form, have a constant composition, and do not change in air and during storage. Such substances include many salts (sodium tetraborate Na2B4O7 10H2O, sodium oxalate Na2C2O4, potassium bichromate K2Cr2O7, sodium chloride NaCl); oxalic acid H2C2O4 2H2O and some others. Substances that meet the listed requirements are called initial or standard.

Precise determination of the concentration of working solutions is one of the main prerequisites for obtaining good results of volumetric analysis. Carefully prepared and tested working solutions are stored under conditions that exclude a change in the concentration of the solution due to evaporation, decomposition of the substance, or contamination from the environment. The concentration of working solutions is periodically checked against standard solutions.

Commercially available fixanals can also be used to prepare titrated solutions. These are glass ampoules containing accurately weighed amounts of various solids or precisely measured volumes of liquids needed to prepare a 1 liter solution with an exact molar equivalent concentration. To prepare a solution from fixanal, the contents of the ampoule are transferred to a 1-liter volumetric flask, after which the substance is dissolved and the volume is adjusted to the mark.

During the titration, it is necessary to establish the moment of the end of the reaction, i.e. the equivalence point, when the amounts of reactants in the mixture become equivalent. For this purpose, indicators are used in titrimetric analysis. Indicators are substances that are added in small quantities to solutions during titration and change color at the equivalence point.

To determine the moment of equivalence, in addition to color, you can use the change in other properties of the solution, but this requires physicochemical measurements. The latter are increasingly being used in volumetric analysis.

In titrimetric analysis, only such reactions are used that satisfy the following conditions:

the interaction between the substance to be determined and the reagent must proceed in certain stoichiometric ratios;

the reaction between the substance to be determined and the reagent must proceed at a high rate;

the chemical reaction between the analyte and the reagent must proceed completely, i.e. the reversibility of the reaction is not allowed;

the reaction between the analyte and the reagent should not be accompanied by any side reactions.

For accurate measurement of volumes, measuring utensils are used: burettes, pipettes, volumetric flasks and volumetric cylinders.

Burettes are designed for titration and precise measurement of the amount of spent reagent. These are graduated glass tubes, the lower end of which is tapered and fitted with either a ground glass stopcock or a rubber tube with a ball stopper connected to a pipette. Burettes are made in capacities from 10 to 100 ml. For particularly accurate analyzes, microburettes of 1 and 2 ml are used. The most commonly used burettes are from 10 to 50 ml. The burette graduation starts from the top, from it downwards there are large divisions of 1 ml to the bottom mark. Whole milliliters are divided into tenths. The volume of liquid poured from the burette is determined by the difference in levels before and after titration. Liquid level readings must be carried out very accurately. The accuracy of readings is hampered by the fact that the burette has a concave meniscus. The visible shape of the meniscus depends on the lighting conditions, so when reading behind the burette, you need to place white paper closely. The eyes should be at the level of the meniscus during the reading. Burettes are filled with a funnel. The top of the burette is covered with a cap so that dust does not get into it. Before filling with the solution, the burette must be rinsed three times with the same solution.

Pipettes are used in cases where it is necessary to measure a certain exact volume of liquid from a prepared solution and transfer it to another vessel. Pipettes are glass tubes with an expansion in the middle and a slight narrowing at the bottom end. The capacity of the pipette is indicated on the top. Pipettes are made with a capacity of 1 ml to 100 ml. Graduated pipettes have divisions of 25, 10, 5, 2, 1 ml. To measure a thousandth of a milliliter, micropipettes of 0.2 and 0.1 ml are also used. Pipettes are stored in special racks in a vertical position. Fill the pipette with the solution using a rubber bulb or draw the solution into the pipette by mouth through the top of the tube. The latter method is not recommended due to the possible ingress of liquid into the mouth. When filling the pipette with a solution, the latter is sucked slightly above the mark and then the upper hole is quickly clamped with the index finger so that the liquid does not spill out of the pipette. The filled pipette is slightly raised so that the tip comes out only from the solution, but not from the vessel from which the solution is taken. Then, keeping the eye at the level of the mark, carefully relieve the pressure of the finger, slightly raising its end, and the liquid flows out drop by drop. As soon as the lower part of the meniscus reaches the mark line, the pipette opening is tightly closed with a finger and the measured liquid is poured into another vessel. The solution is drained from the pipette by touching the pipette tip to the wall of the vessel where the solution is poured. Usually, the solution is allowed to drain freely, or the speed of draining is slowed down by covering part of the top opening of the pipette with a finger. When all the liquid has poured out, you need to wait 20 - 30 seconds, then remove the pipette from the vessel. The droplet of liquid remaining on the pipette tip should not be blown out, as it has been taken into account when calibrating the pipette. When working with a pipette, before filling the latter with a solution, it is necessary to rinse the pipette several times with the same solution.

After finishing work, the pipette should be washed with distilled water.

Volumetric flasks are mainly used to prepare solutions of a certain concentration. These are flat-bottomed vessels with a narrow and long neck. On the neck there is a mark in the form of a ring, up to which the flask must be filled (along the lower edge of the liquid meniscus) in order to obtain the volume indicated on the wide part of the flask. Volumetric flasks are designed for volumes of 50, 100, 200, 500, 1000, 5000 ml. The capacity of the flask is indicated in the inscription on the flask. The flask is closed with a glass stopper. Fill the flask first through a funnel inserted into it, and then from a pipette so that the lower meniscus is opposite the line.

Graduated cylinders are used to measure certain volumes of solutions, when accuracy is not of great importance. They are convenient for mixing and diluting solutions of a certain volume. There are divisions along the height of the cylinder. When measuring, the eye should always be at the same level as the lower meniscus. Graduated cylinders are not used to accurately measure volumes.

The glassware intended for performance of chemical analyzes has to be washed up carefully. This is one of the most important elements of the work, providing accurate results. The criterion for the purity of glassware is the dripping of water droplets from the inner walls. If drops appear on the walls during rinsing, then, when starting work, it is necessary to wash the dishes again. You can use special ruffs. After that, the dishes are filled with a chromium mixture, which oxidizes traces of organic substances on the glass, and kept for some time (up to half an hour). After washing the dishes, the chromium mixture is collected for reuse. After pouring the chromium mixture into a collection flask, the dishes are rinsed first with tap water and then with distilled water. If the dishes must be used dry, they are dried in special drying cabinets.

Titration is carried out as follows:

A clean burette is rinsed 2-3 times with a small amount of working solution to remove residual water.

Mount the burette vertically in the leg of the tripod and fill with the titrated solution to a level slightly above zero.

Part of the solution is lowered into the supplied beaker to displace air from the rubber tube and pipette.

Bring the liquid level to zero. Not a drop of solution should remain on the tip of the burette (it is removed by touching the glass).

Pipette the test solution into the titration flask.

Gradually pour the liquid from the buret into the flask until the equivalence point is established.

When counting the liquid, the eye is held exactly at the level of the meniscus. For colored solutions, the reading is made along the upper meniscus, for uncolored solutions, along the lower one.

At the end of the work, the burette is filled with water above zero division and closed from above with a test tube.

Errors can be made in chemical analyzes, so several parallel measurements are taken. Systematic errors in titrimetric analysis may occur due to incorrect determination of the concentration of working solutions, changes in concentration during storage, inaccuracies in volumetric glassware, incorrect choice of indicator, etc.

The sources of random errors are: the inaccuracy of filling the buret to zero division, the inaccuracy of reading the volume on the burette scale, the uncertainty of the excess of the regent after adding the last drop of the working solution during titration.

Calculations in titrimetric analysis are carried out according to the law of equivalents: at the same molar concentrations of the equivalent, the solutions interact with each other in equal volumes. At various concentrations, the volumes of solutions of interacting substances are inversely proportional to their concentrations:

V1 s(1/z X1) = V2 s(1/z X2) (1)

For both reactants, the product of the molar concentration of the equivalent of its solution and the volume is a constant value. Based on the law of equivalents, various quantitative calculations can be carried out.

So, for example, knowing the molar concentration of the equivalent of one solution, as well as the volumes of solutions used for titration, one can determine the molar concentration and titer of another solution. For example:

To neutralize 20.00 ml of sulfuric acid solution, 12.00 ml of alkali solution with a molar equivalent concentration of 0.2000 mol/l was used. Calculate the molar equivalent concentration and titer of sulfuric acid in this solution.

2 NaOH + H2SO4 = Na2SO4 + 2 H2O

NaOH + S H2SO4 = S Na2SO4 + H2O

It can be seen from the equation that the H2SO4 equivalence factor is equal to S, and the NaOH equivalence factor is equal to 1. Substituting the values ​​into formula (1), we obtain:

c(S H2SO4) = 0.2000 mol/l · 12.00 ml / 20.00 ml = 0.1200 mol/l

t(H2SO4) = c(1/2 H2SO4) · M(1/2 H2SO4) / 1000, g/ml

Hence t(Н2SO4) = 0.1200 mol/l 49 g/m/1000 = 0.005880g/mol

Calculations in titrimetric analysis should be carried out with a high degree of accuracy.

The volumes of solutions are measured to the nearest hundredth of a milliliter, for example: V (HCI) = 10.27 ml or V (NaOH) = 22.82 ml. The concentration of solutions is calculated to the fourth significant figure, for example:

c(NSI)=0.1025 mol/l

c (NaOH)=0.09328 mol/l

t(NSI) = 0.003600 g/ml

Depending on the reaction that underlies the definition, volumetric analysis methods can be divided into the following groups:

Acid-base titration methods or neutralization method

Methods of oxidation - reduction or oxidimetry

Complexonometry method

Deposition methods

Learning tasks and standards and their solutions

Task number 1. In medicine, potassium permanganate is used as an external antiseptic for washing wounds and throats - 0.1-0.5% solution, for gargling - 001 - 01% solution, for gastric lavage - 0.02 - 0.1% solution. Which method of titrimetric analysis can be used to calculate the concentration of a potassium permanganate solution if a titrated solution of oxalic acid is available?

Decision reference

Potassium permanganate is an oxidizing agent, oxalic acid is a reducing agent. Since the reaction between these components is redox, the permanganatometry method can be used to determine the concentration of potassium permanganate.

Task number 2. Determine the molar concentration of the equivalent, and the titer of hydrogen chloride, if 19.87 ml of 0.1 mol/l NaOH solution was used to titrate 20.00 ml of this solution.

V(HCl)= 20.00 ml

V(NaOH)= 19.87 ml

c(NaOH)= 0.1000 mol/l

M (HCl) \u003d 36.5 g / mol

c(HCl) = ?t(HCl) = ?

Decision standard.

The equation of the ongoing reaction:

NaOH + HCl = NaCl + H2O

Thus: f equiv (NaOH) = 1, f equiv (HCl) = 1.

According to the law of equivalents, we find the molar concentration of the HCl solution:

c(NaOH) V(NaOH) = c(NSl) V(HCl)

c(HCl) =mol/l

Based on the value of c(HCl), we calculate the titer of this solution:

t(HCl) =

t(HCl)= 0.003627g/ml

Answer: c(HCl) = 0.09935 mol/l

t(HCl) = 0.003627 g/ml

situational tasks.

Answer: V(NaOH)=12.33 ml.

2. In what cases does the equivalence point lie at pH = 7, at pH<7, при рН>7?

Answer: When a strong acid is titrated with an alkali, the equivalent point coincides with the neutral point; when titrating a weak acid with an alkali, the equivalent point lies at pH values<7, при титровании слабого основания сильной кислотой эквивалентная точка лежит выше нейтральной точки.

3. Lead acetate - Pb(CH3COO)2 - is an astringent for inflammatory skin diseases. A 0.5% solution is used. Calculate the mass of this substance to prepare 100 ml of a 0.5% (mass) solution. What is the mass fraction of lead (%) in this solution? p=1 g/ml.

Answer: m (Pb (CH3COO) 2 \u003d 0.5 g. w% \u003d (Pb) \u003d 0.32%.

Test questions.

1. What value of the solution titer t(HCl) reflects the required degree of accuracy of determinations in titrimetric analysis

a) 0.03 g/ml b) 0.003715 g/ml c) 0.0037578 g/ml) 3.7 g/ml d) 0.0037 g/ml

2. What volume values ​​converge in titrimetric analysis?

a) 2.51 ml; 10.52 ml; 8.78 ml d) 15.27 ml; 15.22 ml; 15.31 ml

b) 5.73 ml; 7.02 ml; 15.76 ml c) 1.07 ml; 5.34 ml; 0.78 ml.

3. What measuring utensils determine the volume of the titrated solution

a) pipette c) volumetric flask b) buretc) flask

4. What reaction underlies the acid-base titration?

a) redox reaction

b) neutralization reaction

c) the reaction of formation of complex compounds

d) a reaction proceeding with the release of heat

5. What solution is called titrated?

a) solution of unknown concentration

b) freshly prepared solution

c) reagent solution of precisely known concentration

d) the solution whose concentration is to be determined

6.What is the equivalence point?

a) this is the end point of the reaction b) this is the start point of the reaction

c) the interaction of two substances d) the point where the volumes are equal

7. On what law are calculations based in titrimetric analysis?

a) the law of conservation of mass of matter b) the law of equivalents

c) Ostwald's dilution law d) Raoult's law

8. For what purpose are pipettes used?

a) for measuring the exact volume of the solution b) for titration

c) for preparing solutions d) for diluting the solution

9. What is the titer of the solution?

a) is the number of grams of solute in 1 liter of solution

b) this is the number of moles of a solute in 1 liter of solution

c) this is the number of moles of a solute in 1 kg of solution

d) is the number of grams of solute in 1 ml of solution

10. What substances are used to determine the equivalence point?

a) indicators b) inhibitors c) promoters d) catalysts

LCAB WORK 2

2.1 Technique of work with laboratory volumetric utensils used in tit rimetric analysis (on water)

...

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The folder contains materials that will help organize a practical part in chemistry for children with disabilities and in distance learning

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MONITORING THE ACHIEVEMENT OF PLANNED RESULTS IN THE COURSE OF CHEMISTRY (FROM WORK EXPERIENCE)

Dushak Olga Mikhailovna

Regional budgetary educational institution "School of distance education", Zheleznogorsk,

Keywords: new Federal State Educational Standard, planned results, chemistry, current control, microskills

Annotation: The article describes the experience of using such forms of control as the Feedback Sheet and the List of Achievements of the Planned Results in the Chemistry course of grades 8-9.

The activity of the teacher within the framework of the new educational standard is result-oriented. The planned result of education, prescribed in the Federal State Educational Standard, is differentiated. The planned results of mastering the curricula are given in two blocks: "The graduate will learn" (basic level) and "The graduate will have the opportunity to learn" (advanced level). On the FIPI website, a teacher and a student can get acquainted with the measuring materials for the final certification of students. For the qualitative passage of the final certification, the student must master the system of concepts, subject knowledge and skills. The teacher is faced with the task of forming this knowledge and skills, creating a system for evaluating the achievement of planned results in the course of ongoing monitoring. Having studied the materials of the new Federal State Educational Standard, methodological literature, and the experience of colleagues, I set about creating my own system for tracking the effectiveness of achieving the planned results when studying the topics of the Chemistry course in grades 8-9. As a basis for the classification, I took the system considered by A.A. Kaverina, senior researcher. Center for Science Education of the Institute for Education Development Strategy of the Russian Academy of Education, Ph.D.

To assess the achievement of the planned results, it is necessary to develop criteria. Criteria should be developed correctly, accessible and reflect the gradual assimilation of knowledge and skills to create comfortable conditions for the child to acquire cognitive experience, to move from the zone of actual development to the zone of proximal development and beyond. During the last academic year, I developed and tested algorithms for completing tasks, feedback sheets, achievement sheets for some sections of the Chemistry course in grades 8-9.

During the educational process, at the beginning of the study of each topic, students are offered a list of concepts for the final test and criteria for evaluating their educational results in the form of skills and micro-skills, reflected in the Feedback Sheets and assignments for them. In the course of studying the topic, the results are noted in the Achievements List. Tasks can be used both when studying a new topic, and when consolidating and summarizing educational material. For example, in the Variety of Chemical Reactions section, skills are worked out: to draw up equations for the electrolytic dissociation of acids, alkalis, salts; compose full and reduced ionic equations of exchange reactions. The feedback sheet that the student receives contains micro-skills for the phased completion of the task, which is also attached. To evaluate their own results, I offer students a simple scale: I can + I can’t-.

Task number 1 Compose salt formulas using the valency value for the metal and acid residue; name the substances, write the dissociation equation (the text of the assignment is given as a fragment).

acids	Metals					One salt dissociation equation
				Fe(II)	Fe(III)
Name
HNO3
Name

Evaluation criteria: I can + I can't -

Task number 2 Compose formulas for the proposed substances, determine the class, write the dissociation equations for these substances: potassium chloride, silver nitrate, sodium carbonate, magnesium sulfate, lead nitrate, potassium sulfide, potassium phosphate (the text of the assignment is given as a fragment).

Feedback sheet _____________________________________________ Full name

Topic: Ionic Equations BASIC!

I can: DATES:				offset
Compose formulas of complex substances by valence
define a class
name a substance
Write the equation for the dissociation of matter

Evaluation criteria: I can + I can not -

Task number 3 Write the equations for the exchange reactions between the proposed pairs of substances. Equalize, compose a complete and reduced ionic equation (the text of the task is given as a fragment).

Feedback sheet ____________________________________________ Full name

Topic: Ionic Equations BASIC!

I can: DATES:				offset
Write the products of an exchange reaction
Arrange odds
Identify substances that do not undergo dissociation
Write down the complete ionic equation
Write an abbreviated ionic equation

Evaluation criteria: I can + I can not -

After the successful completion of tasks of the basic level, the student gets the opportunity to complete tasks of an advanced level, which indicates the formation of the ability to apply the acquired knowledge to solve educational and practical problems in a changed, non-standard situation, as well as the ability to systematize and generalize the knowledge gained.

For example, when performing task number 3 onelevated level, the student can formulate a conclusion about the case in which the ion exchange reactions proceed to the end. Using the Table of Solubility of Acids, Bases and Salts, write examples of molecular equations for these abbreviated ionic equations: Ba 2+ + SO 4 2- \u003d BaSO 4; CO 3 2- + 2H + = H 2 O + CO 2, etc.

Such an organization of the educational process showed a number of advantages: the possibility of an individual trajectory in the assimilation of the topic, the criteria for evaluating the results of work that are understandable to the child and his parents. In the future, it is planned to continue work on the development of assignments for other sections of the course.

Bibliographic list:

1. Kaverina A.A. Chemistry. Planned results. Job system. Grades 8-9: a manual for teachers of educational institutions / A.A. Kaverina, R.G. Ivanova, D.Yu., Dobrotin; ed. G.S. Kovaleva, O.B. Loginova. – M.: Enlightenment, 2013. – 128 p. – (We work according to new standards)

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Grade 8 Practical work on the topic:Soil and water analysis

Experience 1

Mechanical soil analysis

In a test tube (or vial) place the soil (the column of soil should be 2-3 cm). Add distilled water(boiled) the volume of which should be 3 times the volume of the soil.

Close the test tube with a stopper and shake thoroughly for 1-2 minutes, and then arm yourself with a magnifying glass and observe the sedimentation of soil particles and the structure of sediments. Describe and explain your observations.

Experience 2

Obtaining a soil solution and experiments with it

Prepare paperfilter (or cotton, bandage), insert it into the funnel fixed in the tripod ring. Substitute a clean, dry test tube under the funnel and filter the mixture of soil and water obtained in the first experiment. The mixture should not be shaken before filtering. The soil will remain on the filter, and the filtrate collected in the test tube is a soil extract (soil solution).

Place a few drops of this solution on a glass plate and use tweezers to hold it over the burner until the water evaporates.(just leave on the battery).What are you watching? Explain.

Take two litmus papers (red and blue)(if there is!), apply soil solution to them with a glass rod. Draw a conclusion based on your observations:

1. After evaporation of water on the glass ………..

2. Universal litmus paper will not change color if the solution is neutral, will turn red if it is acidic, and blue if it is alkaline.

Experience 3

Determination of water transparency

For the experiment, you need a transparent flat-bottomed glass cylinder.(tumbler) diameter 2-2.5 cm, height 30-35 cm You can use a 250 ml measuring cylinder without a plastic stand. SPECIFY YOUR GLASS DIMENSIONS

We recommend that you test first with distilled water and then with water from a reservoir and compare the results. Place the cylinder on the printed text and pour in the test water, making sure that you can read the text through the water. Note at what height you won't see the font. Measure the heights of the water columns with a ruler. Draw conclusions:

The measured height is called the level of visibility.

If the level of visibility is low, then the reservoir is heavily polluted.

Experience 4

Determination of the intensity of the smell of water

conical flask(jar) fill 2/3 full volume of the investigated water, close tightly with a cork (preferably glass) and shake vigorously. Then open the flask and note the nature and intensity of the smell. Rate the intensity of the smell of water in points, using table 8.

Use table 8 (p. 183).

MAKE A GENERAL CONCLUSION

Preview:

Section V Experimental Chemistry

• Reveal during the performance of a chemical experiment signs indicating the occurrence of a chemical reaction
• Conduct experiments on the recognition of aqueous solutions of acids and alkalis using indicators

Related concepts:

Chemical phenomenon (reaction), experiment, acid, alkali, signs of a chemical reaction, solution, indicators

Signs of a chemical reaction:

Discoloration, odor, precipitation or dissolution, evolution of gas, emission or absorption of heat and light

Task number 1

Feedback sheet __________________________________________ Full name

Topic: Experimental chemistry. Signs of chemical reactions

I can: DATES:				offset
Follow the rules for working with substances
Record the changes that occur to substances during the experiment
Recognize signs of a chemical reaction
Record Observations
Write the reaction equation in molecular form
Formulate a conclusion

Evaluation criteria: I can + I can't -

	Name of experience	Video duration, email address	Signs of a reaction	Reaction equation
	The interaction of acids with metals	37 sec
	Reaction between copper oxide and sulfuric acid	41 sec

Federal Agency for Education Tomsk State University of Architecture and Civil Engineering

I.A. KURZINA, T.S. SHEPELENKO, G.V. LYAMINA, I.A. BOZHKO, E.A. VAYTULEVICH

LABORATORY WORKSHOP ON GENERAL AND INORGANIC CHEMISTRY

Tutorial

Publishing House of Tomsk State University of Architecture and Civil Engineering

UDC 546 (076.5) L 12

Laboratory workshop on general and inorganic chemistry [Text]: textbook / I.A. Kurzina, T.S. Shepelenko, G.V. Lyamina [and others]; under. ed. I.A. Kurzina.

Tomsk: Publishing House Vol. state architect.-builds. un-ta, 2006. - 101 p. – ISBN 5–93057–172–4

AT the textbook provides theoretical information on the main sections of the general course

and inorganic chemistry (classes of inorganic compounds, basic laws and concepts of chemistry, energy effects of chemical reactions, chemical kinetics, solutions, electrochemistry, basic properties of some elements of groups I - VII of the periodic system of D.I. Mendeleev). The experimental part describes the methods of performing seventeen laboratory works. The manual will allow students to prepare more effectively for practical classes and save time when preparing reports on laboratory work. The textbook is intended for all specialties of all forms of education.

ill. 14, tab. 49, bibliography. 9 titles Published by decision of the editorial and publishing council of TGASU.

Reviewers:

Associate Professor of the Department of Analytical Chemistry, KhP TSU, Ph.D. V.V. Shelkovnikov Associate Professor of the Department of General Chemistry, TPU, Ph.D. G.A. Voronova Associate Professor of the Department of Chemistry, TSUAE, Ph.D. T.M. Yuzhakov

university, 2006

Introduction ...............................
Rules for working in a chemical laboratory ....................................................... ...................
Laboratory work number 1. Classes of inorganic compounds...................................
Laboratory work number 2. Determination of the molecular weight of oxygen...................
Laboratory work number 3. Determination of the thermal effect of a chemical reaction.....
Laboratory work number 4. Kinetics of chemical reactions............................................
Laboratory work number 5. Determination of the concentration of the solution. Hardness of water...
Laboratory work number 6. Reactions in electrolyte solutions. Hydrolysis of salts ..........
Laboratory work number 7. Electrochemical processes.............................................
Laboratory work number 8. Chemical properties of metals. Corrosion........................
Laboratory work number 9. Aluminum and its properties....................................................
Laboratory work number 10. Silicon. Hydraulic binders.................................
Laboratory work number 11. Compounds of nitrogen and phosphorus.............................................
Laboratory work number 12. Sulfur and its properties...............................................................
Laboratory work number 13. Chromium subgroup elements..............................................
Laboratory work No. 14. Halogens ............................................... .................................
Laboratory work number 15. Elements of the manganese subgroup.........................................
Laboratory work number 16. Subgroup of the iron family.............................................
Conclusion................................................. ................................................. .........................
Appendix 1. List of essential acids........................................................................
Annex 2. Characteristics acid-base indicators ...............................
Annex 3. The most important physical and chemical values ​​...............................................
Annex 4. The most important physical and chemical constants ................................................
Appendix 5 Relationship between units...........................................
Appendix 6 Prefixes of multiples and submultiples....................................................
Appendix 7. Cryoscopic and ebullioscopic constants of some races
creators ................................................................ ................................................. ......................
Appendix 8		electrolytic dissociation (α) of the most important
electrolytes in 0.1 N solutions at 25 °C.............................................................................
Appendix 9	Constants	dissociation	some electrolytes in aqueous
solutions at 25 °С...............................................................................................................
Annex 10.		solubility	inorganic compounds at
room temperature.........................................................................................................
Appendix 11. Electrochemical series of voltages and standard electrode
potentials at 25 °С...........................................................................................................
Appendix 12. Processes occurring during the electrolysis of aqueous solutions
salts ................................................. ................................................. ................................................
Appendix 13. Periodic system of elements of D.I. Mendeleev ..........................

INTRODUCTION

Chemistry refers to the natural sciences that study the material world around us. The material objects that make up the subject of study of chemistry are chemical elements and their various compounds. All objects of the material world are in continuous motion (change). There are various forms of motion of matter, including the chemical form of motion, which is also the subject of study of chemistry. The chemical form of the motion of matter includes a variety of chemical reactions (transformations of substances). So, Chemistry is the science of the properties of chemical elements and their compounds and the laws governing the transformations of substances.

The most important applied aspect of modern chemistry is the purposeful synthesis of compounds with the necessary and predicted properties for their subsequent application in various fields of science and technology, in particular, to obtain unique materials. It should be noted that chemistry as a science has come a short way to the present day - approximately since the 60s of the XIX century. Over a period that lasted a century and a half, a periodic classification of chemical elements and the doctrine of periodicity were developed, a theory of the structure of the atom, a theory of chemical bonding and the structure of chemical compounds were created, such important disciplines for describing chemical processes as chemical thermodynamics and chemical kinetics appeared, quantum chemistry arose, radiochemistry, nuclear physics. Chemical research has expanded so that certain branches of chemistry - inorganic chemistry, organic chemistry, analytical chemistry, physical chemistry, polymer chemistry, biochemistry, agricultural chemistry and others - became self-

solid independent sciences.

This teaching aid includes two main sections of modern chemistry: "General Chemistry" and "Inorganic Chemistry". The theoretical foundations for understanding the diverse and complex picture of chemical phenomena are laid by general chemistry. Inorganic chemistry introduces substances formed by chemical elements into the concrete world. The authors tried to cover the main issues of the general chemistry course in the shortest possible way. Considerable attention is paid to the theoretical sections of general chemistry: basic laws and concepts of chemistry, chemical thermodynamics, chemical kinetics, properties of solutions, electrochemistry. In the section "Inorganic Chemistry" the main properties of elements of groups I - VII of the periodic system of D.I. Mendeleev. The appendices give the basic physical and chemical properties of inorganic substances. This teaching aid is designed to help students master the basic principles of chemistry, acquire the skills to solve typical problems and conduct experiments in a chemical laboratory.

When conducting laboratory work, it is very important to observe safety precautions. Work with this teaching aid should begin with an acquaintance with the basic rules of work in a chemical laboratory.

RULES OF WORK IN THE CHEMICAL LABORATORY

Safety requirements before starting work:

1. Before performing laboratory work, it is necessary to familiarize yourself with the physical and technical properties of the substances used and formed during the chemical reaction, as well as with the instructions and rules for handling them.

2. Keep the workplace clean and tidy. Only the necessary tools and a workbook should be on the desktop.

Safety requirements during work:

1. The experiment should be started only when the purpose and tasks of it are clearly understood, when the individual stages of the experiment are thought out.

2. Work with poisonous, volatile and caustic substances must be carried out only in a fume hood.

3. In all work, exercise maximum caution, remembering that inaccuracy

and carelessness can lead to an accident.

4. Do not lean over a vessel with boiling liquid. The heated test tube must be held with the opening away from you, as ejection of liquid may occur. Warm the contents throughout the tube, not just from the bottom.

5. After using the reagent, it must be immediately put in place so as not to create a mess in the workplace and not mix up reagents when arranging them at the end of classes.

6. When diluting concentrated sulfuric acid, it is necessary to pour acid into water in small portions, and not vice versa.

7. It is forbidden to work with flammable substances near switched on electrical appliances and burning spirit lamps or burners.

8. You should sniff the substance by directing the vapors towards you with the movement of your hand, and not inhaling them with full breasts.

9. Do not use for experiments substance from cans, packages and droppers without labels or with illegible inscriptions.

10. If acid or alkali comes into contact with the skin, it is necessary to wash the burned area with plenty of water, and then - in case of burns with acid - 3% solution of soda, and in case of burns with alkalis - 1% solution of boric acid.

11. If the reagent gets into the eyes, rinse them with a stream of water, and in case of gas poisoning, provide the victim with fresh air.

12. In order to avoid poisoning, it is strictly forbidden to store and eat food, smoke in the working rooms of chemical laboratories.

Safety requirements at the end of work:

It is necessary to clean up everything spilled, broken and scattered from the table and floor. After completing the experiment, the workplace must be put in order. Do not throw granules and pieces of metal into the sink, but put them in a special vessel and hand them over to the laboratory assistant. No substances from the laboratory can be taken home. After finishing work, you must

thoroughly wash your hands. Report all violations of safety rules and unforeseen situations to the teacher immediately!

I have read and agree to comply with the safety regulations. Signature of the student:

Conducted briefing, checked knowledge of safety regulations Teacher's signature:

Lab #1

CLASSES OF INORGANIC COMPOUNDS

Purpose of work: to study the classes of inorganic compounds, methods for their preparation and chemical properties.

Theoretical part

All chemicals are divided into two groups: simple and complex. Simple substances consist of atoms of one element (Cl2, O2, C, etc.). The composition of the complex includes two or more elements (K2 SO4, NaOH, HNO3, etc.). The most important classes of inorganic compounds are oxides, hydroxides, and salts (figure).

Oxides are compounds consisting of two elements, one of which is oxygen. By functional features, oxides are divided into salt-forming and non-salt-forming (indifferent). Non-salt-forming called oxides that do not form hydrated compounds and salts (CO, NO, N2 O). Salt-forming oxides according to their chemical properties, they are divided into basic, acidic and amphoteric (figure). The chemical properties of oxides are presented in table. one.

Na2O; MgO CuO.

Acid oxides form all non-metals (except F) and metals with a high degree of oxidation (+5, +6, +7), for example SO3; P2 O5 ; Mn2 O7 ; CrO3 .

Amphoteric oxides form some metals in the +2 oxidation state (Be, Zn, Sn, Pb) and almost all metals in the +3 and +4 oxidation states (Al, Ga, Sc, Ge, Sn, Pb, Cr, Mn).

Table 1

Chemical properties of oxides

	Basic oxides		Acid oxides
	Basic oxide + H2O → Base		Acid oxide + H2O → Acid
	CaO+H2O → Ca(OH)2		SO3 +H2O → H2 SO4
	Main oxide + acid. oxide → salt		Acid oxide + Basic oxide → Salt
	CaO+CO2 → CaCO3		SO3 + Na2O → Na2 SO4
	Main oxide + acid → salt + H2O		Acid oxide + base → salt + H2O
	CaO + H2 SO4 → CaSO4 + H2 O		SO3 + 2NaOH → Na2 SO4 + H2 O

Amphoteric oxides

1. Amphoteric oxide + H 2 O →

2. Amph. oxide + acid. oxide → salt 2. Amph. oxide + Basic oxide → Salt

ZnO + N2 O5 → Zn(NO3 )2	ZnO2 + Na2 O → Na2 ZnO2 (in melt)
3. Amph. oxide + Acid → Salt + H2 O 3. Amph. oxide + base → salt + H2O
ZnO + H2SO4 → ZnSO4 +H2O	ZnO+2NaOH → Na2 ZnO2 +H2 O (in melt)
	ZnO + 2NaOH 2 → Na2 (in solution)

INORGANIC COMPOUNDS
			Main
IA: Li, Na, K, Rb, Cs			Me2 O (Me=Li, Na, K, Rb, Cs)
IIA: Mg, Ca, Sr, Ba			MeO (Me=Mg, Ca, Sr, Ba, Cu, Ni)
AMPHOTERIC		Salt-forming	Amphoteric
			EO (E=Be, Zn, Sn, Pb)
			E2 O3 (E=Al, Ga, Cr)
			EO2 (E=Ge, Pb)
			Acidic
			Cl2O
			EO2 (E=S, Se, C, Si)
NOBLE			E2 O3 (E=N, As)
			E2 O5 (E=N, P, As, I)
			EO3 (E = S, Se)
VIIIA: He, Ne, Ar
			Non-salt-forming
			CO, NO, N2O, SiO, S2O
NON-METALS
			Basic (grounds)
VA: N2, P, As
VIA: O2, S, Se			MeOH (Me=Li, Na, K, Rb, Cs)
VIIA: F2 , Cl2 , Br2 , I2			Me(OH)2 (Me=Mg, Ca, Sr, Ba, Cu, Ni)
			Amphoteric
			E(OH)2 (E=Be, Zn, Sn, Pb)
			E(OH)3 (E=Al, Cr)
	HYDROXIDES		Acidic (acids)
			Oxygen-	Acid-free
			HEO2 (E=N, As)	(E=F, Cl, Br, I)
			H3 AsO3
			H2 EO3 (E=Se, C)
			HEO3 (E=N, P, I)
			H3 EO4 (E=P, As)
			H2 EO4 (E=S, Se, Cr)
			HEO4 (E=Cl, Mn)
		Basic salts (hydroxosalts)
			FeOH(NO3 )2 , (CaOH)2 SO4
		Medium salts (normal)
			Na2 CO3 , Mg(NO3 )2 , Ca3 (PO4 )2
		Acid salts (hydrosalts)
			NaHSO4 , KHSO4 , CaH2 (PO4 )2
Classification of inorganic compounds

Hydroxides are chemical compounds of oxides with water. According to chemical properties, basic hydroxides, acid hydroxides and amphoteric hydroxides are distinguished (see figure). The main chemical properties of hydroxides are given in table. 2.

Basic hydroxides or bases are substances that, during electrolytic dissociation in aqueous solutions, form negatively charged hydroxide ions (OH–) and do not form other negative ions. Alkali metal hydroxides that are readily soluble in water, except for LiOH, are called alkalis. The names of the main hydroxides are formed from the word "hydroxide" and the name of the element in the genitive case, after which, if necessary, the degree of oxidation of the element is indicated in brackets by Roman numerals. For example, Fe (OH) 2 is iron (II) hydroxide.

Acid hydroxides or acids are substances that, when dissociated in aqueous solutions, form positively charged hydrogen ions (H + ) and do not form other positive ions. The names of acid hydroxides (acids) are formed according to the rules established for acids (see Appendix 1)

Amphoteric hydroxides or ampholytes are formed by elements with amphoteric properties. Amphoteric hydroxides are called like basic hydroxides, for example, Al (OH) 3 - aluminum hydroxide. Ampholytes exhibit both acidic and basic properties (Table 2).

table 2

Chemical properties of hydroxides

	Foundations
	to C
	Base → Basic oxide + H2O
	to C
	Ba(OH)2 → BaO + H2O
	Base + Acid. oxide → Salt + H2O	2. Acid + Basic oxide →Salt+ H2O
	Ba(OH)2 + CO2 → BaCO3 + H2O		H2 SO4 + Na2 O → Na2 SO4 + H2 O

3. Base + Acid → Salt + H 2 O

Ba(OH)2 + H2SO4 → BaSO4 + 2H2O

Amphoteric hydroxides

1. Amph. hydroxide+Acid. oxide→Salt+H2 O 1. Amf. hydroxide+Basic oxide → Salt+H2 O

Salts are substances whose molecules consist of metal cations and an acid residue. They can be considered as products of partial or complete replacement of hydrogen in the acid by a metal or hydroxide groups in the base by acid residues.

There are medium, acidic and basic salts (see figure). Medium or normal salts are products of complete replacement of hydrogen atoms in acids with a metal or hydroxide groups in bases with an acid residue. Acid salts are products of incomplete replacement of hydrogen atoms in acid molecules by metal ions. Basic salts are products of incomplete replacement of hydroxide groups in bases by acidic residues.

The names of middle salts are made up of the name of the acid anion in the nominative case (Appendix 1) and the name of the cation in the genitive case, for example CuSO4 - copper sulfate. The name of acid salts is formed in the same way as the average ones, but at the same time the prefix hydro is added, indicating the presence of unsubstituted hydrogen atoms, the number of which is indicated by Greek numerals, for example, Ba (H2 PO4) 2 - barium dihydrogen phosphate. The names of basic salts are also formed similarly to the names of medium salts, but at the same time the prefix hydroxo is added, indicating the presence of unsubstituted hydroxo groups, for example, Al (OH) 2 NO3 - aluminum dihydroxonitrate.

Work order

Experience 1. Establishing the nature of oxides

Experience 1.1. Interaction of calcium oxide with water (A), hydrochloric acid (B), caustic soda (C). The environment of the resulting solution in the experiment (A) is checked using an indicator

(Appendix 2).

Observations: A.

Reaction equations:

Experience 1.2. Interaction of boron oxide with water (A), hydrochloric acid (B), caustic soda (C). Experiment (A) is carried out under heating. The environment of the resulting solution in the experiment (A) is checked using an indicator (Appendix 2).

Observations: A.

Reaction equations:

Experience 2 . Preparation and properties of aluminum hydroxide

Experience 2.1. Interaction of aluminum chloride with a lack of sodium hydroxide

No. p / p

Sections, topics

Number of hours

Work program by class

10 cells

11 cells

Introduction

1. Solutions and methods for their preparation

2. Calculations by chemical equations

3. Determination of the composition of mixtures

4. Determination of the formula of a substance

5. Patterns of the course of chemical reactions

6. Combined tasks

7. Qualitative reactions

Introduction to chemical analysis.

Chemical processes.

Chemistry of elements.

Corrosion of metals.

Food chemistry.

Pharmacology.

Final conference: "The value of experiment in the natural sciences."

Total:

Explanatory note

This elective course is designed for students in grades 10-11 who choose a natural science direction, designed for 68 hours.

The relevance of the course lies in the fact that its study will allow you to learn how to solve the main types of calculation problems that are provided for by the high school chemistry course and the program of entrance exams to universities, that is, successfully prepare for the exam in chemistry. In addition, the lack of practical training is compensated. This makes classes exciting and instills skills in working with chemical reagents and equipment, develops observational skills and the ability to think logically. In this course, an attempt was made to make the most of the visibility of a chemical experiment, to enable students not only to see how substances interact, but also to measure the ratios in which they enter into reactions and are obtained as a result of the reaction.

Course objective: expansion of students' ideas about a chemical experiment.

Course objectives:

Repetition of the material discussed in chemistry lessons;

Expansion of students' ideas about the properties of substances;

· Improving practical skills and skills in solving calculation problems for different types;

· Overcoming the formal representation of some schoolchildren about chemical processes.

During the course, students improve their skills in solving computational problems, perform qualitative tasks for the identification of substances in different bottles without labels, and experimentally carry out chains of transformations.

In the course of the experiment in the classroom, five types of skills and abilities are formed.

1. Organizational skills and abilities:

drawing up an experiment plan according to the instructions;

determination of the list of reagents and equipment according to the instructions;

preparation of the report form according to the instructions;

performing the experiment at a given time, using familiar means, methods and techniques in work;

implementation of self-control according to the instructions;

knowledge of the requirements for writing the results of the experiment.

2. Technical skills and abilities:

proper handling of known reagents and equipment;

assembly of devices and installations from finished parts according to the instructions;

performing chemical operations according to the instructions;

compliance with labor safety rules.

3. Measuring skills and abilities:

work with measuring instruments in accordance with the instructions;

knowledge and use of measurement methods;

processing of measurement results.

4. Intellectual skills and abilities:

clarification of the purpose and definition of the tasks of the experiment;

putting forward a hypothesis of the experiment;

selection and use of theoretical knowledge;

observation and establishment of characteristic signs of phenomena and processes according to the instructions;

comparison, analysis, establishment of cause-and-effect relationships,

generalization of the obtained results and - formulation of conclusions.

5. Design skills and abilities:

correction of the simplest malfunctions in equipment, instruments and installations under the supervision of a teacher;

use of ready-made equipment, instruments and installations;

production of the simplest equipment, instruments and installations under the guidance of a teacher;

image of equipment, instruments and installations in the form of a picture.

Knowledge control is carried out when solving computational and experimental problems.

The result of the work on the elective course will be the performance of a test work, including the compilation, solution and experimental implementation of a calculation problem or a qualitative task: determining the composition of a substance or implementing a chain of transformations.

Introduction (1 hour)

Planning, preparing and conducting a chemical experiment. Safety precautions during laboratory and practical work. Rules for the provision of first aid for burns and poisoning with chemical reagents.

Topic 1. Solutions and methods for their preparation (4 hours)

The value of solutions in a chemical experiment. The concept of a true solution. Rules for the preparation of solutions. Technochemical scales and rules for weighing solids.

The mass fraction of a solute in a solution. Calculation and preparation of a solution with a certain mass fraction of a dissolved substance.

Determination of the volumes of solutions using volumetric utensils and the density of solutions of inorganic substances using a hydrometer. Tables of densities of solutions of acids and alkalis. Calculations of the mass of a solute from a known density, volume, and mass fraction of a solute.

Change in the concentration of a solute in a solution. Mixing two solutions of the same substance in order to obtain a solution of a new concentration. Calculations of the concentration of the solution obtained by mixing, the "cross" rule.

Demos. Chemical utensils for the preparation of solutions (glasses, conical and flat-bottomed flasks, volumetric cylinders, volumetric flasks, glass rods, glass funnels, etc.). Preparation of sodium chloride solution and sulfuric acid solution. Technochemical scales, weights. Determination of the volume of solutions of acids and alkalis using a graduated cylinder. Hydrometer. Determination of the density of solutions using a hydrometer. Increasing the concentration of the sodium hydroxide solution by partially evaporating the water and adding more alkali to the solution, checking the change in concentration with a hydrometer. Reducing the concentration of sodium hydroxide in a solution by diluting it, checking the change in concentration using a hydrometer.

Practical work. Weighing on technochemical scales of sodium chloride. Preparation of a sodium chloride solution with a given mass fraction of salt in the solution. Determining the volume of a sodium chloride solution using a graduated cylinder and determining its density using a hydrometer. Determination of the concentration of solutions of acids and alkalis by the values ​​of their densities in the table "Mass fraction of the dissolved substance (in%) and the density of solutions of acids and bases at 20 ° C". Mixing solutions of sodium chloride of various concentrations and calculating the mass fraction of salt, and determining the density of the resulting solution.

Topic 2. Calculations by chemical equations (10 hours)

The practical determination of the mass of one of the reactants by weighing or by volume, density, and mass fraction of the solute in solution. Carrying out a chemical reaction and calculating the equation of this reaction. Weighing the reaction product and explaining the difference between the practical result obtained and the calculated one.

Practical work. Determination of the mass of magnesium oxide obtained by burning a known mass of magnesium. Determination of the mass of sodium chloride obtained by reacting a solution containing a known mass of sodium hydroxide with an excess of hydrochloric acid.

Practical determination of the mass of one of the reacting substances by weighing, conducting a chemical reaction and calculating according to the chemical equation of this reaction, determining the mass or volume of the reaction product and its yield as a percentage of the theoretically possible.

Practical work. Dissolving zinc in hydrochloric acid and determining the volume of hydrogen. Calcination of potassium permanganate and determination of the volume of oxygen.

Carrying out reactions for substances containing impurities, observing the results of the experiment. Calculations with the determination of the mass fraction of impurities in a substance based on the results of a chemical reaction.

Demonstration experiment. Dissolving sodium, calcium in water and observing the results of the experiment in order to detect impurities in these metals.

Practical work. Dissolution of chalk powder contaminated with river sand in a solution of nitric acid.

Determination of the masses of reactants, carrying out a chemical reaction between them, the study of reaction products and the practical determination of a substance in excess. Solving problems to determine the mass of one of the reaction products from known masses of reactants, one of which is given in excess.

Demonstration experiment. The combustion of sulfur and phosphorus, the determination of the substance that is in excess in these reactions.

Practical work. Conducting a reaction between solutions of nitric acid and sodium hydroxide containing known masses of reactants, determining the excess of the reagent using an indicator.

Topic 3. Determination of the composition of mixtures (2 hours)

Carrying out the reaction of a mixture of two substances with a reagent that interacts with only one component of the mixture. Carrying out the reaction of a mixture of two substances with a reagent that interacts with all components of the mixture. Discussion of the results of the experiment. Solving problems for determining the composition of mixtures.

Demonstration experiment. Interaction of a mixture of zinc dust and copper filings with hydrochloric acid. Interaction of a mixture of magnesium powder and zinc dust with hydrochloric acid.

Topic 4. Determining the formula of a substance (6 hours)

The concept of the qualitative and quantitative composition of a substance. Calculation of the molecular weight of a substance based on its hydrogen density, etc. and the mass fraction of the element. Determination of the formula of a substance based on the quantitative data of the reaction products. Determination of the formula of organic substances based on the general formula of the homologous series.

Topic 5. Patterns of chemical reactions (5 hours)

The concept of thermal processes in chemical reactions. Exo- and endothermic reactions. Calculations on thermochemical equations.

Demonstration. The reaction of dilution of concentrated sulfuric acid and the preparation of ammonium chloride.

The concept of reaction rate. Factors affecting the reaction rate. Determination of the reaction rate.

Demonstration. Influence of reaction conditions on its rate.

The concept of chemical equilibrium. Ways to shift chemical equilibrium. Application of this knowledge in chemical production.

Topic 6. Combined tasks (3 hours)

Solving combined problems for different types of block C of the Unified State Examination in chemistry.

Topic 7. Qualitative reactions (3 hours)

The concept of a qualitative reaction. Determination of substances using the solubility table of acids, bases and salts, characterization of visible changes in processes. Determination of inorganic substances found in different bottles without labels, without the use of additional reagents. Implementation of transformations of inorganic and organic substances.

Demonstration experiment. Identification of solutions of iron (II) sulfate, copper (II) sulfate, aluminum chloride, silver nitrate using sodium hydroxide solution. Identification of solutions of sodium chloride, potassium iodide, sodium phosphate, calcium nitrate using a solution of silver nitrate and nitric acid.

Implementation of a chain of transformations.

Practical work. Determination in numbered bottles without labels of solutions of silver nitrate, sodium hydroxide, magnesium chloride, zinc nitrate without the use of additional reagents.

Topic 8. Introduction to chemical analysis (6 hours)

Introduction. Chemistry, man and modern society. Introduction to chemical analysis. Fundamentals of qualitative analysis. Fundamentals of analytical chemistry. Solution of typical calculation problems.

Practical work. Carrying out analysis to detect traces of blood and saliva in the issued samples. Analysis of chips and soft drinks.

Topic 9. Chemical processes (6 hours)

Characteristics of chemical processes. Chemical process, its signs. Crystals in nature. Crystallization of substances and its dependence on various factors. Chemical processes in the human body. Biochemistry and physiology.

Practical work. crystallization of matter. Growing crystals in the laboratory. Decomposition of hydrogen peroxide by blood enzymes.

Topic 10. Chemistry of elements (5 hours)

The essence of a chemical reaction. Solving problems involving substances of various classes and determining the type of chemical reaction. Chemical reactions that take place without changing the oxidation state of chemical elements. Reactions that go with a change in the degree of oxidation of chemical elements. Ion exchange reactions.

Practical work. Salt precipitation.

Topic 11. Corrosion of metals (3 hours)

The concept of corrosion. Signs of a corroded surface. Chemical and electrochemical corrosion. Corrosion protection.

Practical work. Methods for protecting metal surfaces from corrosion.

Topic 12. Food chemistry (7 hours)

Chemistry and nutrition. The importance of proteins, fats and carbohydrates for good nutrition. Factors affecting the absorption of the most important components of food. Chemical characteristics of the processes occurring in the digestive tract. "Live" and "dead" food. Chemistry of vegetarianism and meat-eating. Flavorings, preservatives, dyes and flavor enhancers.

Practical work. Determination of artificial colors in food. Isolation of proteins from biological objects.

Topic 13. Pharmacology (4 hours)

The concept of pharmacology. Recipe and prescription. Homeopathy, its chemical bases. Contraindications and side effects, chemism.

Practical work. The effect of antibiotics and nitrates on soil microflora.

Topic 14. Final conference: "The value of experiment in the natural sciences" (3 hours)

From natrochthymia to chemotherapy (drug chemistry). Chemistry of food biology. Solving typical chemical problems for entering the exam.

Requirements for learning outcomes

In the classroom of the elective course "Experimental problems in chemistry", students must strictly comply with the safety requirements for laboratory and practical work, know the rules for providing first aid for burns and poisoning with chemical reagents.

After studying the proposed course, students should:

be able to make measurements (mass of a solid with the help of technochemical scales, the volume of the solution with the help of volumetric utensils, the density of the solution with the help of a hydrometer); prepare solutions with a given mass fraction of the solute; determine the percentage concentration of solutions of acids and alkalis according to the tabular values ​​of their densities; plan, prepare and conduct simple chemical experiments related to dissolving, filtering, evaporating substances, washing and drying precipitates; obtaining and interaction of substances belonging to the main classes of inorganic compounds; determination of inorganic substances in individual solutions; the implementation of a chain of transformations of inorganic compounds;

solve combined problems, including elements of typical calculation problems:

determination of the mass and mass fraction of a solute in a solution obtained by various methods (dissolving a substance in water, mixing solutions of different concentrations, diluting and concentrating a solution);

determination of the mass of the reaction product or the volume of gas from the known mass of one of the reactants; determination of the yield of the reaction product as a percentage of the theoretically possible;

determination of the mass of the reaction product or the volume of gas from the known mass of one of the reactants containing a certain proportion of impurities;

determination of the mass of one of the reaction products from the known masses of the reactants, one of which is given in excess.

Bibliography:

1. Gabrielyan O.S. General chemistry: tasks and exercises. M.: Education, 2006.

2. Gudkova A.S. 500 tasks in chemistry. M.: Education, 2001.

3. Tasks of the All-Russian Chemistry Olympiads. M.: Exam, 2005.

4. Labiy Yu.M. Solving problems in chemistry using equations and inequalities. M.: Enlightenment, 2007

5. Magdesieva N.N., Kuzmenko N.E. Learn to solve problems in chemistry. M.: Education, 2006.

6. Novoshinsky I.I. Types of chemical problems and ways to solve them. M.: Oniks, 2006.

7. Okaev E.B. Chemistry Olympiad. Mn.: TetraSystems, 2005.

8. KIMs of the Unified State Examination in Chemistry for different years

Number

lesson

(sections, topics)

Quantity

hours

Dates

Lesson equipment

Homework

1. Introduction.

PSCE D.I. Mendeleev, portraits of scientists

Introduction.

2. Solutions and methods for their preparation

Alcohol lamp, test tube rack, test tubes, flame test wire, filter paper, evaporation cup, universal indicator paper, solutions of nitric acid, barium chloride, sodium hydroxide, lime water, silver nitrate

Mass fraction of the dissolved substance.

Molar concentration and molar concentration equivalent.

Solubility of substances.

Practical work No. 1: "Preparation of a solution of a certain concentration by mixing solutions of various concentrations."

3. Calculations by chemical equations

Alcohol lamp, tripod, tongs, spatula, beaker, test tubes, dropper, measuring cylinder, filter funnel, filter paper, solutions of nitric acid, silver nitrate, hydrochloric acid, D.I. Mendeleev's PSCE, solubility table, calculator

Determination of the mass of the reaction product from the known mass of one of the reactants.

Calculation of volume ratios of gases.

Tasks related to the determination of the mass of the solution.

Calculation of the mass, volume, amount of substance of the reaction product, if one of the reactants is given in excess.

Carrying out a reaction between substances containing known masses of reactants, determining the excess using an indicator.

Determination of the yield of the reaction product as a percentage of the theoretically possible.

Calculation of impurities in reactants.

4. Determination of the composition of mixtures

Alcohol lamp, tripod, glass, measuring cylinder, evaporation cup, filter paper, magnesium, sulfuric acid, copper (II) oxide, magnesium carbonate, sodium hydroxide, hydrochloric acid

Determination of the composition of the mixture, all components of which interact with the specified reagents.

Determination of the composition of the mixture, the components of which selectively interact with the specified reagents.

5. Determination of the formula of a substance

Derivation of the formula of a substance based on the mass fraction of elements.

The derivation of the molecular formula of a substance based on its density in hydrogen or in air and the mass fraction of the element.

The derivation of the molecular formula of a substance by the relative density of its vapors and the mass, volume or amount of the substance of the combustion products.

Derivation of the formula of a substance based on the general formula of the homologous series of organic compounds.

6. Patterns of chemical reactions

PSCE D.I. Mendeleev, solubility table, task cards

Calculations according to thermochemical equations.

The rate of chemical reactions.

chemical balance.

7. Combined tasks

PSCE D.I. Mendeleev, solubility table, task cards

Combined tasks.

8. Qualitative reactions

Wide test tube with vent tube, tripod, stopwatch, gas syringe, measuring cylinder, zinc granules and powder, dilute hydrochloric acid, hydrogen peroxide solution, manganese (IV) oxide, copper (II) oxide, zinc oxide, sodium chloride, potato slices, liver pieces.

Methods for determining inorganic and organic substances.

Experimental determination of inorganic substances.

Experimental determination of organic substances.

34 hour

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• Characteristics of a student from the place of internship
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• Biography of Faraday. Great scientists. Michael Faraday. discovery of electromagnetic rotation
• Modern innovations in education

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