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This chemistry lesson is studied according to O.S. Gabrielyan’s teaching materials (2 hours per week) in the chapter “Dissolution. Solutions. Properties of electrolyte solutions" in the 4th quarter of 8th grade. Lesson type – learning new material. During the lesson, students consolidate knowledge about the types of chemical bonds; get acquainted with the essence and mechanism of electrolytic dissociation.
Increasing cognitive motivation in the lesson is facilitated by demonstration of experiments on the electrical conductivity of solids and electronic presentation.
The study of new material occurs through demonstration experiments, analysis of diagrams and drawings, as well as the use of an electronic presentation of the Microsoft Power Point program. During the lesson, students develop the following skills: observe, compare, analyze, and draw conclusions. When studying new material, interdisciplinary connections with physics are used.
The training session combines frontal and individual work.
The result of the work is: intensification of the work of the teacher and students in the lesson; Students consolidate their understanding of the types of chemical bonds, master the concepts of electrolyte and non-electrolyte, and study the essence and mechanism of electrolytic dissociation.
Lesson reflection is carried out in the form of a chemical dictation.
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Municipal educational institution
"Basic secondary school No. 12"
Chemistry lesson
8th grade
ELECTROLYTIC DISSOCIATION
Chemistry teacher
Kharitonova M.V.
Moore
2012-2013 academic year
Explanatory note
This chemistry lesson is studied according to O.S. Gabrielyan’s teaching materials (2 hours per week) in the chapter “Dissolution. Solutions. Properties of electrolyte solutions" in the 4th quarter of 8th grade. Lesson type – learning new material. During the lesson, students consolidate knowledge about the types of chemical bonds; get acquainted with the essence and mechanism of electrolytic dissociation.
Increases cognitive motivation in the classroomdemonstration of experiments on the electrical conductivity of solids and electronic presentation.
The study of new material occurs through demonstration experiments, analysis of diagrams and drawings, as well as the use of an electronic presentation of the Microsoft Power Point program. During the lesson, students develop the following skills: observe, compare, analyze, and draw conclusions. When studying new material, interdisciplinary connections with physics are used.
The training session combines frontal and individual work.
The result of the work is: intensification of the work of the teacher and students in the lesson; Students consolidate their understanding of the types of chemical bonds, master the concepts of electrolyte and non-electrolyte, and study the essence and mechanism of electrolytic dissociation.
Lesson reflection is carried out in the form of a chemical dictation.
The purpose of the lesson: studying the essence of the new concept “electrolytic dissociation”
Tasks:
Educational objectives:
- Ensure that students learn new concepts: electrolyte, non-electrolyte, electrolytic dissociation.
- Establish the dependence of the electrical conductivity of solutions on the type of chemical bond and crystal structure of the substances.
- Reveal the essence and mechanism of the process of electrolytic dissociation using the example of substances with ionic and polar covalent bonds.
- To deepen students' knowledge about ionic and covalent polar bonds, the properties of the main classes of inorganic substances.
Developmental tasks:
- Developing the ability to observe experiments, analyze diagrams and drawings, and take notes.
Development of cognitive experience of schoolchildren.
- Continue to form a worldview about the dependence of the properties of substances on composition and structure.
Educational tasks:
Continue building motivation for learning activities.
Continue to form ideas about the positive role of chemistry to explain ongoing processes in nature.
Lesson type : a lesson in learning new material.
Technologies used: The lesson is built using modern information technologies - Microsoft Power Point.
Forms of training organization: a combination of frontal and individual work.
Interdisciplinary connections: physics (two types of charges).
Lesson equipment:
Multimedia equipment;electrical conductivity tester substances.
Basic concepts:electrolyte, non-electrolyte, electrolytic dissociation.
Expected results: intensification of the work of the teacher and students in the lesson; Students consolidate their understanding of the types of chemical bonds, master the concepts of electrolyte and non-electrolyte, and study the essence and mechanism of electrolytic dissociation.
LESSON PLAN
STAGE I - MOTIVATIONAL-ORIENTATION
Introduction to a new topic. Repetition of types of chemical bonds.
STAGE II - OPERATIONAL AND EXECUTIVE
1. Electrolytes and non-electrolytes.
2. The structure of the water molecule.
3. The mechanism and essence of electrolytic dissociation.
4. Svante Arrhenius - message from a student.
5. Degree of dissociation. Strong and weak electrolytes.
STAGE III - EVALUATIVE-REFLECTIVE.
Students complete assignments.
LESSON SUMMARY.
Today we are starting to study a new topic: “Electrolytic dissociation.” The purpose of the lesson will be to reveal the essence of a new concept for you - electrolytic dissociation.
You already know that chemical bonds between atoms can be of two types: ionic and covalent. Give examples of substances with these types of bonds. What is the type of chemical bond in compounds of atoms from three or more different elements: salts of oxygen-containing acids and bases?
Thus, salt crystals are composed of ions: “+” charge for the metal and “-” charge for the acid residue Na+ Cl - , K + NO - 3 , Na + 3 PO 3- 4
Solid bases also have a crystal lattice with “+” charged metal ions and “-” charged hydroxy ions: NaOH, Ca(OH) 2
If the compound contains only non-metal atoms (O, H, C), then all bonds are covalent. Such substances as glucose, sugar, alcohol, etc. contain neutral molecules - there are no ions.
II. 1. Differences in the nature of the chemical bond affect the behavior of substances in solutions, since most reactions occur in solutions.
From your physics course, you know that the ability of solutions to conduct electric current is determined by the presence of electrical charge carriers - ions. To do this, use a device for testing electrical conductivity (brief description of the device).
Demonstration of experiments on the electrical conductivity of solids and their solutions, followed by their discussion.
Thus, a salt solution, unlike pure water and solid salt, conducts an electric current, since it contains freely moving ions. Like salt solutions, alkali solutions conduct electric current. Salts and alkalis conduct electric current not only in solutions, but also in melts: upon melting, the crystal lattice is destroyed into ions and they begin to move freely, transferring an electric charge.
SUBSTANCES
ELECTROLYTES NON-ELECTROLYTES
“SUBSTANCES, SOLUTIONS OR MELTS OF WHICH CONDUCT ELECTRIC CURRENT ARE CALLED ELECTROLYTES.”
These are salts, acids, alkalis (electric current is transmitted in them due to the movement of “+” and “-” ions).
Now let’s test solutions of substances with covalent bonds - sugar, alcohol - for electrical conductivity. The light bulb does not light, which means that solutions of these substances do not conduct electric current.
“SUBSTANCES IN WHICH SOLUTIONS DO NOT CONDUCT ELECTRICITY ARE CALLED NON-ELECTROLYTES.
CONCLUSION: charge is carried by free ions that have the ability to move. This means that the behavior of substances in an aqueous solution depends on their structure.
2. Let us remember the structure of the water molecule. In a water molecule there is a covalent polar bond between the O and H atoms. The electron pairs connecting the atoms are shifted to O, where a partially “-” charge is formed, and H has a partially “+” charge. The bonds of each H atom with O in water form an angle of 104.5 with each other 0 , due to which the water molecule has an angular shape. A polar water molecule is depicted as dipoles
3. Let us consider the mechanism of dissociation using the example of a NaCl salt solution. When salt dissolves, the water dipoles are oriented with oppositely charged ends around the “+” and “-” ions of the electrolyte. Mutual attractive forces arise between the ions of the electrolyte and the water dipole. As a result, the connection between the ions weakens, and the ions move from the crystal to the solution (Fig. 42 of the textbook). The sequence of the dissociation process of substances with ionic bonds (salts and alkalis) will be as follows:
a) orientation of molecules - water dipoles near crystal ions
b) hydration (interaction) of water molecules with ions of the surface layer of the crystal
c) dissociation (decay) of the electrolyte crystal into hydrated ions.
The ongoing processes can be reflected in a simplified way using the equation: NaСl = Na+ + Cl -
Electrolytes, in whose molecules there is a covalent polar bond (for example, HCl), dissociate similarly, only in this case, under the influence of water dipoles, the covalent polar bond is converted into an ionic one and the sequence of processes will be as follows.
a) orientation of water molecules around the poles of an electrolyte molecule
b) hydration (interaction) of water molecules with electrolyte molecules
c) ionization of electrolyte molecules (conversion of a covalent polar bond into an ionic one).
d) dissociation (decay) of electrolyte molecules into hydrated ions.
A simplified equation for the dissociation of hydrochloric acid looks like this:
HCl = H + + Cl -
An ion surrounded by a hydration shell (water molecules) is calledhydrated.The presence of a hydration shell prevents the transition of ions into the crystal lattice. The formation of hydrated ions is accompanied by the release of energy, which is spent on breaking the bonds between the ions in the crystal.
Thus, when salts, alkalis and acids are dissolved, these substances break down into ions.
“The process of an electrolyte breaking down into ions when it is dissolved in water or melted is called electrolytic dissociation.”
The theory that explains the special behavior of electrolytes in a molten or dissolved state by decomposition into ions is calledtheory of electrolytic dissociation.
4. In electrolyte solutions, along with ions, there are also molecules. Therefore, electrolyte solutions are characterizeddegree of dissociation, which is denoted by the Greek letter α (“alpha”).
The degree of dissociation is the ratio of the number of particles disintegrated into ions (N d ), to the total number of dissolved particles (N P):
α=N d /N P
The degree of electrolyte dissociation is determined experimentally and is expressed in fractions or percentages. If α=0, then there is no dissociation, and if α=1, or 100%, then the electrolyte completely disintegrates into ions. Different electrolytes have different degrees of dissociation, that is, the degree of dissociation depends on the nature of the electrolyte. It also depends on the concentration: as the solution is diluted, the degree of dissociation increases.
Based on the degree of electrolytic dissociation, electrolytes are divided into strong and weak.
Strong electrolytes –electrolytes that, when dissolved in water, almost completely dissociate into ions. For such electrolytes, the degree of dissociation tends to unity.
Strong electrolytes include:
1) all soluble salts;
2) strong acids, for example: H 2 SO 4, HCl, HNO 3;
3) all alkalis, for example: NaOH, KOH.
Weak electrolytes- These are electrolytes that, when dissolved in water, almost do not dissociate into ions. For such electrolytes, the degree of dissociation tends to zero.
Weak electrolytes include:
- weak acids – H 2 S, H 2 CO 3, HNO 2;
- aqueous ammonia solution NH 3 *H 2 O;
- water.
III. CONCLUSIONS and CONCLUSION.
What substances are called electrolytes? Give examples. Why do these substances conduct electricity?
What substances are called non-electrolytes? Give examples.
What is meant by electrolytic dissociation?
What does the degree of dissociation indicate?
How are electrolytes classified according to the degree of dissociation?
Chemical dictation
Write down the substances. Underline electrolytes with one line, non-electrolytes with two lines. Arrange the charges.
Liquid ammonia, calcium chloride solution, sulfuric acid, potassium nitrate, potassium hydroxide, acetone, calcium phosphate, benzene, sugar solution, nitric acid, calcium carbonate, hydrogen iodide.
Students will complete the assignment followed by a test.
Classification of substances SUBSTANCES ELECTROLYTES NON-ELECTROLYTES NaCl, NaOH, KNO 3 Sugar, glucose, alcohol SUBSTANCES, SOLUTIONS OR MELTS OF WHICH CONDUCT ELECTRIC CURRENT ARE CALLED ELECTROLYTES. SUBSTANCES IN WHICH SOLUTIONS DO NOT CONDUCT ELECTRICITY ARE CALLED NON-ELECTROLYTES.
Structure of the water molecule O H H - + 104.5 0
Scheme of electrolytic dissociation of a polar hydrogen chloride molecule H + CL - + + + + + + H + + - + + + + + + CL - + + + + + H + + - + + + + C L - + - + + + + +
“The process of an electrolyte breaking down into ions when it is dissolved in water or melted is called electrolytic dissociation.” 1887 Svante Arrhenius
Classification of electrolytes ELECTROLYTES STRONG WEAK NaCl, NaOH, KNO 3 NH 4 OH, HNO 2
Chemical dictation Write down the substances. Underline electrolytes with one line, non-electrolytes with two lines. Arrange the charges. Liquid ammonia, calcium chloride solution, sulfuric acid, potassium nitrate, potassium hydroxide, acetone, calcium phosphate, benzene, sugar solution, nitric acid, calcium carbonate, hydrogen iodide.
2
7
Anions Cations Anode Cathode - +
Solution Crystal NaCl Na + + Cl H2OH2O H2OH2O Fig.4.
10 Solution HCl H + + Cl - H2OH2O H2OH2O Rice HCl Cl - H+H+ + - H+H Cl-Cl-
14 Screening test. Option 1. Option 2. 1. Non-electrolytes include: 1) sodium carbonate 2) ethyl alcohol 3) hydrochloric acid 4) zinc nitrate 1. Non-electrolytes include: 1) barium chloride 2) sugar 3) sulfuric acid 4) potassium carbonate 2 With the formation of metal cations and anions, the acid residue dissociates: 1). copper (II) hydroxide 2). sodium hydroxide 3). aluminum chloride 4). carbonic acid 2. With the formation of metal cations and anions of the acid residue, the following dissociates: 1) sucrose 2) sodium hydroxide 3) aluminum bromide 4) nitric acid 3. Both substances in the group are electrolytes: 1). CH4, CO2 2). C2H5OH, HNO3 3). CaO, BaSO4 4). NaCl, KOH 3. Both substances in the group are electrolytes: 1). glycerin, SO2 2). CuCl2, KOH 3). BaO, K2SO4 4). Fe(OH)3, H2SiO3 4. Most hydrogen ions are formed during dissociation is equal to: 1). HI 2). H2CO3 3). H2S 4). H2SiO3 4. Most hydrogen ions are formed during dissociation is equal to: 1). H3PO4 2). H2SO4 3). HNO3 4). HF 5. The sum of the coefficients in the dissociation equation of aluminum sulfate is equal to: 1). 4 2). 6 3). 2 4) The sum of the coefficients in the equation for the dissociation of sodium carbonate is equal to: 1). 4 2). 3 3). 2 4). 1
Lesson objectives:
- Educational: learn the definitions of scientific concepts: “electrolytes”, “non-electrolytes”, “electrolytic dissociation”, “cations”, “anions”; explain these important concepts using a demonstration experiment; explain the essence and mechanism of the dissociation process;
- Educational: develop the cognitive activity of students, develop the ability to observe, draw conclusions, and explain the course of the experiment. Develop an interest in chemistry, develop logical thinking.
- Educational: increase cognitive activity and activity of students.
Lesson type: combined.
The motto of the lesson: “No vessel can hold more than its volume, except the vessel of knowledge, it is constantly expanding.” Arabic proverb.
During the classes
1. Organizational moment.
2. Introduction.
Introductory conversation between teacher and students.
Electric current is the directed movement of charged particles. In metals, such directed movement is carried out due to relatively free electrons. But it turns out that not only metals, but also solutions and melts of salts, acids, and bases can conduct electric current.
In 1887, the Swedish scientist Svante Arrhenius formulated the principles of the theory of electrolytic dissociation of substances, and Russian chemists V.A. Kistyakovsky, I.A. Kablukov. supplemented it with ideas about the hydration of ions.
3. Studying new material.
Electrolytic dissociation theory (EDT):
1. Electrolytes are substances whose solutions and melts conduct electric current. These are soluble acids, salts, bases, i.e. substances with covalent polar and ionic bonds. Demonstration experiment: study of the electrical conductivity of solutions of NaCl, HCl, KOH, sugar, water.
2. Nonelectrolytes are substances whose solutions and melts do not conduct electric current. These are substances insoluble in water, as well as substances with non-polar or low-polar covalent bonds, organic substances, liquid oxygen, nitrogen, water, insoluble bases, salts, acids.
3. Electrolytic dissociation is the process of decomposition of an electrolyte into ions.
NaCl -> Na + + Cl - HCl -> H + + Cl -
KOH -> K + + OH -
4. In solutions or melts of electrolytes, ions move chaotically, but when current is passed, positively charged ions are attracted to the cathode (-) and are called cations, and negatively charged ions are attracted to the anode (+) and are called anions. The dissociation process is reversible. 5. Ions differ from atoms both in structure and properties. In aqueous solutions, ions are in a hydrated state.
The dissociation mechanism is explained by the fact that electrolytes, under the influence of a solvent, spontaneously dissociate (break up) into ions. Dissociation can also occur during melting of solid electrolytes (thermal dissociation).
4. Physical exercise.
5. Fixing the material.
1. Divide substances into electrolytes and non-electrolytes: potassium sulfate, calcium carbonate, benzene, oxygen, potassium hydroxide, glucose, sulfuric acid, barium hydroxide, water, sulfur.
Monitoring the completion of the task: self-test from the board.
2. Select substances that can dissociate into ions: barium sulfate, aluminum nitrate, sodium hydroxide, nitrogen, sugar, hydrochloric acid.
3. Write down the dissociation equations for these substances.
Monitoring the completion of the task: work in pairs.
Screening test.
Creative task.
If copper sulfate is dissolved in water, then a blue coloration of the solution is observed and the solution conducts current, but if copper sulfate is dissolved in gasoline, then no coloration is observed and the solution does not turn blue. Explain this phenomenon.
6. Summing up.
At the end of the lesson, we need to talk again about what we learned today. Announce grades. And praise the guys for a good job.
Thus, for a lesson, you can give more than one grade to each student. And learn new material with ease, in an accessible and interesting way for children.
7. Homework.
1, (Rudzitis G. E., Felrman F. G.) Radetzky p. 38, option 1-4 (1 task).
Modern techniques and methods of education: Problem-search, formulation and solution of interdisciplinary issues; performing complex tasks to compare objects; working with tables using NIT tools.
Description of the organization of students' creative activity: Conversation; answering the question after watching the experiment, independent and practical work; assessment of one's own knowledge; creative homework.
Description of pedagogical ideas and initiatives: Visualization of the experiment using multimedia; testing with a set time for each question; creative homework
Methods and technologies of teaching: problem-based - search learning, developmental learning, development of logical thinking, group work, pair work.
Results: The main result of this development is a noticeable increase in the quality of training.
Quality of irradiation (based on the results of diagnostic control work):
2007 -2008 - 72%
2008 -2009 - 80%
This lesson is devoted to the study of the topic “Electrolytic dissociation”. In the process of studying this topic, you will understand the essence of some amazing facts: why solutions of acids, salts and alkalis conduct electric current; Why is the boiling point of an electrolyte solution higher than that of a non-electrolyte solution.
Topic: Chemical bond.
Lesson:Electrolytic dissociation
The topic of our lesson is “ Electrolytic dissociation" We will try to explain some amazing facts:
Why do solutions of acids, salts and alkalis conduct electric current?
Why does the boiling point of an electrolyte solution always be higher than the boiling point of a non-electrolyte solution of the same concentration?
Svante Arrhenius
In 1887, the Swedish physicist chemist Svante Arrhenius, While studying the electrical conductivity of aqueous solutions, he suggested that in such solutions substances disintegrate into charged particles - ions, which can move to the electrodes - a negatively charged cathode and a positively charged anode.
This is the reason for the electric current in solutions. This process is called electrolytic dissociation(literal translation - splitting, decomposition under the influence of electricity). This name also suggests that dissociation occurs under the influence of an electric current. Further research showed that this is not the case: ions are onlycharge carriers in solution and exist in it regardless of whether it passes throughcurrent solution or not. With the active participation of Svante Arrhenius, the theory of electrolytic dissociation was formulated, which is often named after this scientist. The main idea of this theory is that electrolytes spontaneously disintegrate into ions under the influence of a solvent. And it is these ions that are charge carriers and are responsible for the electrical conductivity of the solution.
Electric current is the directed movement of free charged particles. You already know that solutions and melts of salts and alkalis are electrically conductive, since they consist not of neutral molecules, but of charged particles - ions. When melted or dissolved, the ions become free carriers of electric charge.
The process of decomposition of a substance into free ions when it dissolves or melts is called electrolytic dissociation.
Rice. 1. Scheme of decomposition into sodium chloride ions
The essence of electrolytic dissociation is that ions become free under the influence of a water molecule. Fig.1. The process of decomposition of an electrolyte into ions is represented using a chemical equation. Let us write the dissociation equation for sodium chloride and calcium bromide. When one mole of sodium chloride dissociates, one mole of sodium cations and one mole of chloride anions are formed. NaCl⇄ Na + + Cl -
When one mole of calcium bromide dissociates, one mole of calcium cations and two moles of bromide anions are formed.
CaBr 2 ⇄ Ca 2+ + 2 Br -
Note: since the formula of an electrically neutral particle is written on the left side of the equation, the total charge of the ions must be equal to zero.
Conclusion: upon dissociation of salts, metal cations and anions of the acid residue are formed.
Let us consider the process of electrolytic dissociation of alkalis. Let us write the dissociation equation in a solution of potassium hydroxide and barium hydroxide.
When one mole of potassium hydroxide dissociates, one mole of potassium cations and one mole of hydroxide anions are formed. KOH⇄ K + + OH -
When one mole of barium hydroxide dissociates, one mole of barium cations and two moles of hydroxide anions are formed. Ba(OH) 2 ⇄ Ba 2+ + 2 OH -
Conclusion: During the electrolytic dissociation of alkalis, metal cations and hydroxide anions are formed.
Water-insoluble bases practically are not exposed electrolytic dissociation, since they are practically insoluble in water, and when heated they decompose, so it is not possible to obtain a melt.
Rice. 2. Structure of hydrogen chloride and water molecules
Consider the process of electrolytic dissociation of acids. Acid molecules are formed by polar covalent bonds, which means that acids consist not of ions, but of molecules.
The question arises: how then does the acid dissociate, that is, how do free charged particles form in acids? It turns out that ions are formed in acid solutions precisely during dissolution.
Let's consider the process of electrolytic dissociation of hydrogen chloride in water, but for this we will write down the structure of the molecules of hydrogen chloride and water. Fig.2.
Both molecules are formed by a polar covalent bond. The electron density in a hydrogen chloride molecule is shifted towards the chlorine atom, and in a water molecule - towards the oxygen atom. A water molecule is able to abstract a hydrogen cation from a hydrogen chloride molecule, resulting in the formation of a hydronium cation H 3 O + .
The equation for the reaction of electrolytic dissociation does not always take into account the formation of the hydronium cation - usually they say that a hydrogen cation is formed.
Then the dissociation equation for hydrogen chloride looks like this:
HCl⇄ H + + Cl -
When one mole of hydrogen chloride dissociates, one mole of hydrogen cation and one mole of chloride anions are formed.
Stepwise dissociation of sulfuric acid
Consider the process of electrolytic dissociation of sulfuric acid. Sulfuric acid dissociates stepwise, in two stages.
I-stage of dissociation
At the first stage, one hydrogen cation is separated and a hydrogen sulfate anion is formed.
II - stage of dissociation
At the second stage, further dissociation of hydrogen sulfate anions occurs. HSO 4 - ⇄ H + + SO 4 2-
This stage is reversible, that is, the resulting sulfate ions can attach hydrogen cations and turn into hydrogen sulfate anions. This is shown by the reversibility sign.
There are acids that do not dissociate completely even at the first stage - such acids are weak. For example, carbonic acid H 2 CO 3.
We can now explain why the boiling point of an electrolyte solution will be higher than the boiling point of a non-electrolyte solution.
During dissolution, the molecules of the solute interact with the molecules of the solvent, for example, water. The more particles of a solute there are in one volume of water, the higher its boiling point will be. Now imagine that equal amounts of an electrolyte substance and a non-electrolyte substance were dissolved in equal volumes of water. The electrolyte in water will disintegrate into ions, which means the number of its particles will be greater than in the case of dissolution of a non-electrolyte. Thus, the presence of free particles in the electrolyte explains why the boiling point of an electrolyte solution will be higher than the boiling point of a non-electrolyte solution.
Summing up the lesson
In this lesson, you learned that solutions of acids, salts and alkalis are electrically conductive, since when they dissolve, charged particles are formed - ions. This process is called electrolytic dissociation. When salts dissociate, metal cations and anions of acidic residues are formed. When alkalis dissociate, metal cations and hydroxide anions are formed. When acids dissociate, hydrogen cations and anions of the acid residue are formed.
1. Rudzitis G.E. Inorganic and organic chemistry. 9th grade: textbook for general education institutions: basic level / G. E. Rudzitis, F.G. Feldman. M.: Enlightenment. 2009 119 p.: ill.
2. Popel P.P. Chemistry: 8th grade: textbook for general education institutions / P.P. Popel, L.S. Krivlya. -K.: IC “Academy”, 2008.-240 p.: ill.
3. Gabrielyan O.S. Chemistry. 9th grade. Textbook. Publisher: Bustard: 2001. 224s.
1. No. 1,2 6 (p.13) Rudzitis G.E. Inorganic and organic chemistry. 9th grade: textbook for general education institutions: basic level / G. E. Rudzitis, F.G. Feldman. M.: Enlightenment. 2009 119 p.: ill.
2. What is electrolytic dissociation? What classes of substances belong to electrolytes?
3. Substances with what type of bond are electrolytes?
