Questions and exercises on discipline «Inorganic Chemistry» for the specialty «Chemical technology of inorganic substances»: educational-methodical handbook 9786010420618

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AL-FARABI KAZAKH NATIONAL UNIVERSITY

QUESTIONS AND EXERCISES ON DISCIPLINE «INORGANIC CHEMISTRY» for the specialty «Chemical technology of inorganic substances» Educational-methodical handbook Stereotypical publication

Almaty «Qazaq university» 2020

UDC 546 (075.8) LBC 24.74 я 73 Q 93 Recommended for the Academic Council of the Faculty of Chemistry and Chemical Technology and Editorial and Publishing Council of the Kazakh National University named after Al-Farabi (Protocol №4 from 13.07.2016) Reviewer PhD Sh.N. Nazarkulova Compilers: S.M. Romanova, O.I. Ponomarenko, I.V. Matveyeva

Q 93

Questions and exercises on discipline «Inorganic Chemistry» for the specialty «Chemical technology of inorganic substances»: educational-methodical handbook / comp.: S.M. Romanova, O.I. Ponomarenko, I.V. Matveyeva. – Ster. pub. – Almaty: Qazaq university, 2020. – 202 р. ISBN 978-601-04-2061-8 The educational-methodical handbook contains questions and exercises in a test form for the course «Inorganic Chemistry». The educational-methodical handbook can be recommended for self-study of students enrolled in the specialty «Chemical technology of inorganic substances», and will also be useful to teachers, students, master and PhD students of higher educational institutions of chemical specialties. Educational-methodical handbook is published in authorial release. Пособие содержит вопросы и упражнения в виде тестов по курсу «Неорганическая химия». Рекомендовано для самостоятельной работы студентов ВУЗов, обучающихся по специальности «Химическая технология неорганических веществ», будет полезно преподавателям, студентам, магистрантам, PhD докторантам высших учебных заведений химических специальностей. Учебно-методическое пособие издается в авторской редакции.

UDC 546 (075.8) LBC 24.74 я 73 ISBN 978-601-04-2061-8

 Comp.: Romanova S.M., Ponomarenko O.I., Matveyeva I.V., 2020  Al-Farabi KazNU, 2020

4. Bibliography

CONTENT PREFACE .........................................................................................4 THE MAIN CHAPTERS OF THE SUBJECT «INORGANIC CHEMISTRY» ........................................................8 1. Basic concepts and laws of chemistry ........................................8 2. The structure of atom and the periodic system of chemical elements......................................................................................16 3. Inorganic compounds .................................................................35 4. Chemical bonding and molecular structure ................................42 5. Complex compounds ..................................................................60 6. Chemical thermodynamics .........................................................68 7. Chemical kinetics. Chemical equilibrium ..................................81 8. General properties of solutions ...................................................105 9. Electrolyte solutions ...................................................................123 10. Hydrolysis of salts ......................................................................135 11. Redox reactions ..........................................................................146 12. Electrochemical processes ..........................................................169 TABLE OF CORRECT ANSWERS ................................................192 BIBLIOGRAPHY .............................................................................199

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Questions and exercises on discipline «Inorganic Chemistry»

PREFACE

Nowadays there is more and more information about the elements and their compounds. Inorganic compounds and materials based on them are becoming more diverse and more widely used. In laboratories new methods of synthesis of substances are developed, already known methods are improved, new types of chemical reactions involving inorganic substances and compounds are opened. All this requires a deep knowledge of the properties of chemical elements, laws of their changes, properties of compounds of elements and their transformations. The aim of the teaching of inorganic chemistry is to form students' knowledge on the theoretical foundations of chemistry and properties of their simple and complex inorganic substances, to teach students to predict possibility and direction of chemical reactions, to establish the relationship between the structure of matter and its chemical properties. In the handbook a modern, integrated presentation of the basic concepts, terminology and laws of chemistry are presented in a very brief form. They are entered sequentially, in accordance with the basic theoretical sections of the course. After a brief theoretical part the test tasks with the correct answer are presented, that allows to fix the theoretical material. Tasks in the test form allow detecting on time problems in knowledge with short expenditure of time and have teaching character. This handbook can be recommended for self-study in preparation for lessons, midterm and final control of university students enrolled in the specialty «Chemical technology of inorganic substances», and will also be useful to teachers, students, undergraduates, PhD students of higher educational institutions of chemical specialties. 4

Preface

№ 1 1

2

3

4

Сontent 2 The basic concepts and laws of chemistry. Atomic and molecular doctrine. The basic concepts of chemistry. Atoms, molecules, relative atomic mass, mole. The determination of molecular mass. Chemical signs, formulas, equations. Stoichiometric laws of chemistry: mass conservation, constancy of composition, simple multiple proportions, simple volume relations, equivalents, Avogadro. Classification of chemical reactions on the basis of changes in the number and composition of the reactants, the oxidation state of elements, reversibility, thermal effects, aggregate state and presence of a catalyst. The structure of atoms and the periodic system of chemical elements. The composition and the model of structure of atom. The quantummechanical model of atom. The quantum numbers. Atomic orbitals. The Pauli principle. Aufbau and Hund principle, the order of filling of atomic orbitals. Electronic and electronic-graphic formulas of atoms of elements. Normal and excited states of atoms. The valence and the oxidation state of element. The significance of the periodic law and the structure of the periodic table of chemical elements of D.I. Mendeleyev. Periodic changes of some properties of atoms, elements and their compounds. Inorganic compounds. The classes of inorganic compounds and their genetic relationship. Characterization of inorganic hydroxide from the standpoint of atomic structure and the nature of electrolytic dissociation. The strength and thermal stability of acids and bases. Types of salts, their production and properties. Theories of acids and bases: Arrhenius, Brønsted and Lewis. Chemical bonding and structure of molecules. The basic concepts of chemical bonding. The types of chemical bonds: ionic, covalent, metallic, hydrogen and coordination. The mechanisms of bond formation: exchange and donor-acceptor. The method of valence bonds and the method of molecular orbitals. The features of the chemical bond: energy, length, directivity, saturation, polarity and bond angle. Types of overlap and hybridization of atomic orbitals. The geometry of molecules. Influence of polarity of molecules on the physical-chemical properties of the substance. Types of intermolecular interaction. Physical state of the substance. 5

Questions and exercises on discipline «Inorganic Chemistry»

1 5

6

7

8

9

2 Complex compounds. Complex compounds, their nomenclature and classification. Coordination theory of formation of complex compounds of Werner. The structure of complexes: internal and external sphere, complexing agent, ligands, charge and coordination number of complexing agent. The nature of the chemical bond in complex compounds. Electrolytic dissociation and constant of instability of aqueous solutions of complex compounds. Production and properties of complex compounds. Chemical thermodynamics. The basic concepts of chemical thermodynamics: systems, processes, parameters, functions, laws. Thermal effects of chemical reactions. Laws of thermochemistry of Lavoisier-Laplace and Hess. Thermodynamic functions: entropy, internal energy, enthalpy, Gibbs energy, Helmholtz energy, chemical potential. The ability and directivity of spontaneous chemical process. The relationship and the calculations of thermodynamic functions. Chemical kinetics. Chemical equilibrium. The fundamentals of chemical kinetics. Kinetic characteristics of chemical reactions: molecularity, order, rate, constant, activation energy, half-life. Factors affecting rate of reaction: concentration, temperature, pressure, catalyst, nature of reactants. The theory of active collisions. Homogeneous, heterogeneous and enzymatic catalysis. Conditions and chemical equilibrium constant. Thermodynamics of equilibrium. The shift of chemical equilibrium. Le Chatelier's principle. Factors influencing on shifting of equilibrium: concentration, pressure and temperature. General properties of solutions. General characteristics of solutions. Classification of solutions. Physical-chemical nature of process of dissolution. The laws of ideal solutions: Raoul, Van't Hoff, Konovalov. Solubility of substances. Factors influencing on the process of dissolution of substances. Thermodynamics of dissolution process. The concept of solubility product of sparingly water-soluble electrolyte. Conditions, methods of dissolution and precipitation. Methods of expression of quantitative composition of solutions and their recalculations. Types of solution concentration. The electrolyte solutions. Electrolyte solutions and electrolytic dissociation. The strength of electrolytes, degree and constant of dissociation. Theories and 6

Preface

1

10

11

12

2 mechanisms of electrolytic dissociation (Arrhenius, Debye-Huckel, Mendeleyev). Interionic interaction in electrolyte solutions. The ionic strength of electrolyte. Factors affecting the depth of electrolytic dissociation. Electrolytic dissociation of various classes of inorganic compounds. Ionic reactions, their directivity. Hydrolysis of salts. Ion product of water. Constant of water. pH value of aqueous solutions of various acids, bases and salts. Degree and constant of hydrolysis. Factors affecting on the depth of hydrolysis. Hydrolysis of salts. The mechanism of hydrolysis of salts. Reversible and irreversible hydrolysis. Redox reactions. Basic concepts of redox reactions: oxidizing, reducing agents, oxidation, reduction, electronic balance, molar mass of equivalent of oxidizer and reducer. Typical oxidants and reductants. Defining of role of substance in redox depending on the oxidation state of atom in it. Factors affecting the depth of redox. Compiling and equalizing of redox. Types of redox: intermolecular, intramolecular, disproportionation and comproportionation. Electrochemical processes. The basic concepts of electrochemical processes. The electrode potential and types of electrodes. Voltage range. Activity of metals with water and acids. Nernst equation. Redox potential as a measure of redox agents. The Daniel Jacoby galvanic cell. The scheme, electromotive force and thermodynamics of electrochemical cell. The electrolysis of melts and solutions of electrolytes. Faraday's law. Corrosion of metals.

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Questions and exercises on discipline «Inorganic Chemistry»

THE MAIN CHAPTERS OF THE SUBJECT «INORGANIC CHEMISTRY»

1. Basic concepts and laws of chemistry The law of conservation of mass and energy is the most important law of nature. It was formulated by M.V. Lomonosov in 1760. The modern formulation: in isolated system sum of masses and energies is constant. An isolated system is a system that does not have an exchange of mass or energy with environment. There is a relationship between mass and energy according to equation Е = mc2. The main quantitative laws of chemistry. 1. The law of constant composition. Chemically pure substances have the same quantitative composition, there is no matter by which method they were obtained. 2. The law of equivalents. All substances react with each other in equivalent amounts. Equivalent is real or notional particle of matter that can replace, add, or be equivalent to one hydrogen ion in any other way. 3. The law of multiple proportions. If two elements form between each other a number of different compounds, to the same mass of one of them refers such mass of other element, that relate to each other as simple integers. For example, the mass ratio C:O in CO and CO2 are 12:16 and 12:32. Therefore, the mass ratio of carbon associated with a constant mass of CO2 and oxygen in CO, is 2:1. 8

The main chapters of the subject «Inorganic Chemistry»

Calculation of the molar mass of equivalents of substance The molar mass of equivalent of acid is calculated by dividing of the molar mass of the acid on its equivalent. Мeq(HNО3) = М(HNО3) = 63 g/mol·eq Мeq(Н2SО4) = 1/2 М(Н2SО4) = 49 g/mol·eq Molar mass of equivalent of hydroxide is calculated similarly. Мeq(NаОН) = М(NaOH) = 40 g/mol·eq Molar mass of equivalent of salt is calculated by dividing the molar mass of salt to the product of the valence of the metal forming a salt by the number of its particles in the formula. Мeq(KNО3) = М(KNО3) = М g/mol·eq. Мeq(Ва3(РО4)2) = 1/2·1/3·М(Ва3(РО4)2) = 1/6·М g/mol·eq. Example 1. 0.304 g of Mg displaced 0.0252 g of hydrogen. Calculate the equivalent of magnesium. Solution. 0.304 g of units of Mg displaced 0.0252 g of units of hydrogen, E units of mass of Mg will displace 1.008 units of mass of hydrogen. Consequently,

Example 2. Calculate the mass of 1,8 l of H2S, if the volume of gas was measured at 98.64 kPa, and 17 °C. Solution. Volume of H2S, normalized to normal conditions, is:

The mass of

22.4

l

of H2S is equal to 34.08 g «

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Questions and exercises on discipline «Inorganic Chemistry»

1. Find the correct modern formulation of the law of conservation of mass. 1. Weight of substances before reaction is equal to weight of substances after reaction. 2. The energy of substances before and after chemical reaction remains unchanged. 3. In closed system sum of masses of substances and total energy before and after the chemical reaction remains constant, i.e. Σm = const and ΣE = const. 4. Weight of substance and its movement remain unchanged. 5. There is no correct answer. 2. Find author, formulated the law of definite proportions 1. Lomonosov 2. Lavoisier 3. Proust 4. Berthollet 5. Bertsellius 3. Find stoichiometric laws of chemistry 1. The law of conservation of energy 2. The law of multiple proportions 3. The law of conservation of mass 4. The law of equivalents 5. The Periodic Law 6. The law of conservation of mass of gas 7. The Dalton's law of stoichiometric interaction of substances 8. The law of mass action 4. Find the correct formulation of the law of multiple proportions 1. In an isolated system, Σm = const and ΣE = const. 2. Any chemically pure substance has a constant composition and properties. 3. If two elements form between each other several chemical compounds, the weight of one of the elements in these compounds is attributable to same mass of another, related to each other as small integers. 4. In chemical reactions reactants interact multiply their equivalents. 5. There is no correct answer. 10

The main chapters of the subject «Inorganic Chemistry»

5. Choose the correct formulation of the law of equivalents 1. Substances interact with each other in amounts corresponding 1/3 of their equivalents. 2. Substances interact with each other in amounts corresponding one equivalent mass of oxygen. 3. Substances interact with each other in amounts corresponding their equivalents. 4. Substances interact with each other in amounts corresponding 22.4 liters of hydrogen. 5. There is no correct answer.

to to to to

6. Choose the correct formulation of the Avogadro’s law 1. In equal volumes of gases at identical conditions contains the same number of molecules 2. In equal volumes of gases at 00k and a pressure of 1 atmosphere contains the same number of molecules 3. At normal conditions volumes of gaseous substances is always the same 4. At normal conditions in the same volumes of gases number of molecules are not always the same 5. There is no correct answer. 7. Select the correct formula for the calculation of molecular mass of substances 1. 2. 3. 4. 5. 8. How to determine the molecular mass of substances? 1. According to the formula as sum of atomic masses of the atoms of molecule of substance 2. Double value of equivalent m = 2e 3. Equivalent value divided by valence m = e/v 4. By empirical formula 5. There is no correct answer. 11

Questions and exercises on discipline «Inorganic Chemistry»

9. Select mathematical expression of consequence of the Avogadro’s law 1. 2 E = mc 2. PV = RT 3. 4. 5. 10. Select how to determine atomic mass of any element 1. Based on the Einstein's law E = mc2 2. According to the law of constant composition and the law of equivalents 3. According to the rule of Dulong and Petit, the method of Kannitsaro, the phenomenon of isomorphism, according to place of element in the periodic system of D.I.Mendeleyev 4. According to the equation of Clapeyron-Mendeleyev 5. According to the Avogadro’s law 6. According to the law of multiple proportions 11. Select the correct value of «Avogadro» 1. The number of atoms per 1 g of hydrogen equal to 6.022·10 23 2. The number of atoms in 8 g of oxygen equal to 6.022·10 23 3. The number of atoms in 12 g of 12C isotope equal to 6.022·1023 4. The number of structural units in one equivalent of hydrogen 5. The number of structural units in one equivalent of oxygen 12. Select the method for determination of the molecular mass of any substance 1. The law of Dulong and Petit 2. Method, based on isomorphism law 3. The mass-spectroscopic method 4. Avogadro's law, according to equation of Clapeyron-Mendeleyev 5. According to the periodic table of the elements of D.I. Mendeleyev 6. The law of multiple proportions 13. Select the correct definition of «mole» of substances 1. The mass of the atoms, expressed as relative atomic units. 12

The main chapters of the subject «Inorganic Chemistry»

2. The amount of substance containing the same amount of molecules, atoms, ions, electrons, or other structural units as atoms in 12 g of isotope 12C. 3. The amount of the substance containing the same structural units as atoms in 1 g of hydrogen. 4. The amount of a substance containing the same structural units as atoms in 16 g of oxygen. 5. There is no correct answer. 14. Select the correct definition of «equivalent» of element 1. Atomic mass of element expressed in atomic units. 2. Such amount of element, which is connected with one mole of hydrogen atoms or replaces the same number of hydrogen atoms in chemical reactions. 3. The mass of 1 mole of substance. 4. The mass of 1 mole of atoms. 5. There is no correct answer. 15. The expression follows from the law: 1. Conservation of mass 2. Avogadro 3. Multiple relations 4. Equivalents 5. From atomic theory, and the definition of equivalent 6. Constancy of composition 16. Avogadro constant is 6.02·1023, as a result: 1. Mole is a number of substances amounting Avogadro's number (NA = 6.02·1023) of discrete particles (structural components of system) 2. Mole is amount of substance amounting 1/2 of Avogadro's number 3. Mole is amount of substance equal to double value of Avogadro's number 4. Mole is amount of substance equal to triple value of Avogadro's number 5. Mole is mass of substance 6. Mole is number of structural units per unit of volume 13

Questions and exercises on discipline «Inorganic Chemistry»

17. Relative molecular mass of substances (Mr) is immeasurable value which: 1. Expresses molecular mass in oxygen units and is sum of relative atomic masses of the chemical elements of molecule 2. Expresses molecular mass in hydrogen units, equal to sum of atomic masses of molecule 3. Expresses molecular mass in 1/4 of the oxygen units, equal to sum of atomic masses of molecule 4. Expresses molecular mass in carbon units, which consists of relative atomic masses of chemical elements of molecule 5. Equal to 1/12 of mass of oxygen atom 6. There is no correct answer. 18. The equation makes it possible to identify: 1. Molecular mass of gases 2. Molecular mass of liquids 3. Molecular mass of substances 4. Atomic mass of substances 5. Gas constant 6. Volume 19. What volume of hydrogen (n.c.) is obtained by reacting of 0.1 mole of zinc with an excess of HCl? Zn+2HCl=H2+ZnCl2 1. 22.4 l 2. 2.24 l 3. 44.8 l 4. 4.48 l 5. 224 l 6. 224·10 -2 l 20. The equivalence factor is equal to 1 for … 1. K2SO3 2. AgNO3 3. Mg(NO3)2 4. CuSO4 5. NaNO3 6. KCl 21. Mass of aluminum in 200 g of aluminum sulfide is equal to… 1. 2.7 ·10 g 14

The main chapters of the subject «Inorganic Chemistry»

2. 3. 4. 5. 6.

0.27·102 g 720·10 -4 g 7.2 ·10 g 0.71·102 g 0.72·103 g

22. During the decomposition of 2.17 grams of mercury oxide 0.17 g of oxygen was obtained. How much mercury was obtained at the same time? 1. 0.2·10 g 2. 0.17 g 3. 1.60 g 4. 2.0 g 5. 2.17 g 6. 0.02·102 g 7. 3.34 g 23. How much molecules does one mole of phosphorus oxide contain? 1. 3.01·1023 2. 6.02·1023 3. 60.2·1022 4. 12.06·1023 5. 1.01·1023 6. 0.60·1023 7. 0.602·1024 24. Content of molecules is … in 54 g of water. 1. 3.01·1023 2. 1.806·1024 3. 6.02·1023 4. 180.6·1022 5. 12.06·1023 6. 18.06·1023 7. 0.60·1023 25. Determine molecular mass of gas with a density by hydrogen equal to 14. 1. 28 g/mol 2. 16·10 g/mol 3. 32 g/mol 15

Questions and exercises on discipline «Inorganic Chemistry»

4. 64·10 g/mol 5. 71 g/mol 6. 42 g/mol 7. 2.8·10 g/mol 26. The relative density of the gas by air is 0.5. What is the relative molecular mass of the gas? 1. 14.5 2. 53 3. 1.45·10 4. 29 5. 2.9·10 6. 58. 7. 5.3·10 27. The number of molecules in 220 g of carbon dioxide is equal to… 1. 3.01·1023 2. 6.02·1023 3. 30.1·1023 4. 60.2·1023 5. 301·1022 6. 3.01·1024

2. The structure of atom and the periodic system of chemical elements The electronic structure of atom. Main particles of atom are presented in the following table: particles proton neutron electron

symbol p n е

mass, m, kg 10-27 10-27 10-31

charge, K 1.602.10-19 0 1.602.10-19

The nucleus of atom has a positive charge. The charge of the nucleus is determined by number of protons. An atom is electrically neutral, as nuclear charge is compensated by charge of electrons. 16

The main chapters of the subject «Inorganic Chemistry»

The mass of the nucleus consists of the mass of protons and neutrons. The mass of atom is taken equal to the mass of the nucleus, i.e., electron mass is negligible. The most important for the chemical properties of elements are nuclear charges, but not atomic masses. This is proved by the chemical properties of isotopes and isobars. Isotopes are chemical elements which have identical nuclear charges, but different atomic masses. Сl35 37 17 Cl 17

17р + 18n 17р + 20n

Chemical properties of atoms of chlorine-35 and chlorine-37 are identical. Isobars are chemical elements with different charges of the nuclei, but with the same atomic masses (18Ar40, 19K40, 20Са40). Chemical properties of Ar, K, Ca are different. Electron shell of an atom. The features of microparticles 1. The microparticles emit and absorb energy discretely. 2. Any microparticle is simultaneously a particle and a wave. The microparticles have a mass and energy, i.e. they are characterized by particle properties, but when moving microparticles obey wave laws. In 1924 De Broglie deduced an equation that relates mass of microparticle with a wavelength: λ = h/m ∙ υ. 3. The third feature of microparticles is so-called uncertainty principle. The principle is that it is impossible accurately to indicate the coordinates of the microparticle in the space and its speed. 17

Questions and exercises on discipline «Inorganic Chemistry»

The system of quantum numbers. The first postulate of Niels Bohr. There are stationary orbits in the hydrogen atom. Revolving on them the electron does not emit or absorb energy. Niels Bohr calculated radii using the stationary orbits of the principal quantum number. n is the principal quantum number, n = 1,2,3,4, ... + ∞. The second postulate of Niels Bohr. The transition of an electron from one stationary state (E2) to another (E1) is accompanied by the emission of a quantum of monochromatic radiation (λ = const). n1 = 1

r2 = 0.53 Ǻ

n1 = 2

r2 = 2.12 Ǻ

Е = -13.6 1/n2 eV, where: n is the principal quantum number.

EP

E3 E2

increasing distance from the nucleus the potential energy of electrons increases.

E1

Stationary orbits are called energy levels. Later based on the uncertainty principle we abandoned the concept of flat orbits proposed by Bohr, and moved on to the concept of the electron cloud, or orbitals. Orbital (electron cloud) is the most probable location of an electron in a certain volume of perinuclear space. Beyond this space the probability of finding of the electron is quite small (less than 5%). Orbital radii have the values calculated by Bohr for stationary orbits. The principal quantum number has two functions: it determines the size of the electron cloud; it determines its energy reserve. The next quantum number is an orbital quantum number. Orbital quantum number corresponds to the value of the orbital angular momentum of the electron motions. 18

The main chapters of the subject «Inorganic Chemistry»

l is the orbital quantum number. It is closely related to the main quantum number and has values 0 ... (n-1). n 1 2 3 4

l 0(s) 0(s) 1(p) 0(s) 1(p) 2(d) 0(s) 1(p) 2(d)3(f)

The orbital quantum number describes the energy sublevels in the electron shell of an atom. The orbital quantum number specifies the configuration of sublevels. According to quantum-mechanical calculations s-orbitals are shaped like a ball, p-orbital – dumbbell shape, d- and f-orbitals have more complex forms. At one level, the energy of sublevels increases in the series: Es < E p< Ed< Ef. There are magnetic fields in the atom. They are oriented in space sublevels strictly in a certain way. The magnetic quantum number takes the values of integers: -l ... 0 ... + l. l 0(s) 1(p) 2(d) 3(f)

mI value 0 -1...+1 -2, …+2 -3, …+3

number 1 3 5 7

s – sublevel is expressed once; p – sublevel is expressed three times; d – sublevel is expressed five times; f – sublevel is expressed seven times. 19

Questions and exercises on discipline «Inorganic Chemistry»

Three quantum numbers n, l, ml are used to describe the orbitals. The fourth quantum number is spin. It describes the intrinsic angular momentum of the electron, and takes the values, equal to ± 1/2. The electrons can be rotated only in two mutually antithetical directions, showing as (+)↑↓(-). The laws that determine the position of the electrons in the atom. 1. Any particle tends to minimum reserve of potential energy. The electron of the hydrogen atom occupies the lower energy level; 1H 1s1 is electronic formula of the hydrogen atom. – electron diagram of hydrogen atom

2. Pauli exclusion principle Two electrons with the same values of all four quantum numbers cannot be in the atom. Thus, the Pauli exclusion defines electronic capacity of orbitals, sublevels and levels. Electronic capacity of levels is calculated using the following formula: N = 2n2, where: N is the number of electrons on this level, n is the principal quantum number. 3. Hund principle At this energy sublevel electrons are arranged in such a way that their total spin was maximal. 1s2 2s2 2p3

7N

Σs = ± 1/2 · 3 = 1.5

4. The first Aufbau principle First electrons fill orbitals with a smaller sum of principal and orbital numbers, and then orbitals with a larger value of sum of these two numbers. 20

The main chapters of the subject «Inorganic Chemistry»

Σ1(n + l) < Σ2(n + l) 1s 2s 2p 3s 3p 3d 4s 4p Σ(n+l) 1 2 3 3 4 5 4 5

According to the first Aufbau principle first electrons fill ns-orbital, then (n-1)d, which have a larger stock of potential energy. For example, first electrons fill 4s orbital, and then 3d orbital. 2 6 0 18Ar…3s 3p 3d 2 6 0 1 19K…3s 3p 3d 4s 2 6 0 2 20Ca…3s 3p 3d 4s 1 2 21Sc…3d 4s

5. The second Aufbau principle If two orbitals have the same value of the sum of principal and orbital numbers, first electrons fill orbital, whose principal quantum number has less value. Σ1(n + l) = Σ2(n + l) 1s 2s 2p 3s 1 2 3 3

From two orbitals with the same value of the sum of n and l (2p and 3s) first 2p orbital accept electrons. Periodic table of D.I. Mendeleyev. The table consists of 7 periods. The first three periods are short, the last four periods are long. The physical meaning of the period number is that the number of the period corresponds to the principal quantum number. Formation of short periods The capacity of the first energy level is equal to two electrons (N = 2), therefore, the first period consists of two elements: 21

Questions and exercises on discipline «Inorganic Chemistry»

s-elements

s-elements are called elements, in which s-sublevels are filled with electrons.

The capacity of the second energy level N = 8. The length of the second period is 8 elements. s-elements p-elements

Due to the first Aufbau principle length and the construction of the third period repeat exactly the second period: two s-elements and six p-elements. Each period begins with two s-elements which, except hydrogen and helium, are the most active metals. Each active period ends by nonmetals, except noble gases – chemically inert substances. A sign of the metallicity of elements is their ability to lose their valence electrons. Measure of metallicity of elements is a measure of their reducing capacity. The metallicity of elements has a quantitative characteristic, it is ionization energy EI, eV/at. Ionization energy is an energy required to remove an electron from an atom. The lower the energy, the more active metal is this element. An electron divorced from the atom spontaneously, if EI≤40 eV/at. The ionization potential also characterizes an electron detachment from an atom, UI, V/at. A sign of nonmetallicity of elements is the ability to accept electrons, i.e., oxidizing ability. A quantitative characteristic of nonmetallicity of element is the electron affinity, F, eV/at. Electron affinity is the energy required to detach an adopted electron. 22

The main chapters of the subject «Inorganic Chemistry»

The higher electron affinity, the stronger oxidizing agent, i.e. nonmetal, is this element. There is a total characteristic of the electron affinity and ionization energy. It is the relative electronegativity of elements.

The relative electronegativity shows the ability of atoms to attract electrons when bonding with other atoms. Electronegativity can be quantified and build elements in a series. The most frequently used series of electronegativity of elements was proposed by the American chemist L. Pauling. Element Li F Na Cl Be Mg

Z 3 9 11 17 4 12

R, nm 0.55 0.064 0.189 0.099 0.113 0.160

EI, eV/at 5.39 17.4 5.14 12.07 9.32 7.65

F, eV/at 3.61 3.45

EN 1,0 4.0 0.9 3.0 1.5 1.2

Electronegativity is measured in relative terms. The most electronegative from all elements is fluorine (F), it electronegativity in Pauling scale is taken equal to 4.0. The remaining elements in comparison with fluorine have a lower electronegativities. Formation of long periods The fourth period is the first long period (18 elements). s-elements p-elements

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Questions and exercises on discipline «Inorganic Chemistry»

d-elements

The fifth period. The length and structure of the fifth period is exactly the same as the length and structure of the fourth period. The sixth period. 55Cs 56Ba 57La

6s1 6s2 5d16s2

Lanthanum receives the first electron in the 5d sublevel, then, according to the second Aufbau principle filling of sublevel 5d stops and filling of sublevel 4f begins. 58Сe 71Lu 72Hf 80Hg

4s1 5s2 5p6 5d1 6s2 4f14 5s2 5p6 5d1 6s2 5d2 6s2 5d10 6s2

After filling of 4f sublevel filling of sublevel 5d continues; d-elements reappear. The period finishes by six p-elements. Thus, the 6th period has the following structure: s-elements – 2, d-elements – 1, f-elements – 14, d-elements – 9, p-elements – 6. There are totally 32 elements in it. The seventh period has exactly the same length and structure as the sixth period. All transuranic elements (starting from 93Np) are artificial. In the long periods pattern of changes in the properties of the elements is the same as in the small, only slower. All s-elements (except H and He) are the most active metals. All d- and f-elements are also metals. p-elements are partly metals and partly non-metals. Groups of the periodic table of D.I. Mendeleyev. The periodic table of D.I. Mendeleyev includes 8 groups. The physical meaning of the group number is the group number corresponds to the valence of its constituent elements. 24

The main chapters of the subject «Inorganic Chemistry»

If the element has a variable valence, the number of group corresponds to the highest valency of the element. Each group is divided into main (A) and adverse (B) subgroups. Main subgroup contains elements of short and long periods (s- and p-elements). Adverse subgroups include d- and f-elements, i.e. elements of only long periods. Elements constituting one subgroup have similar chemical properties, as have similar valence states. The chemical properties of elements are caused by their valence states. The valence state of the element depends on its position in the periodic table of D.I. Mendeleyev. All elements of one subgroup have the same configuration of valence states, but different quantum numbers. With the increasing of the principal quantum number of elements in this subgroup metallic properties enhance, which is due to increasing of intermediate electron layers between the nucleus of the atom and the valence layer. The elements from the same group, but different subgroups have different valence states and different chemical properties. 17Cl

3s23p5

Active nonmetal

3d54s1

25Mn

metal of average activity

The elements from one group have the same valence. In the case of different valence, the total valence is the highest valence. 1, 3, 5, 7 +7 HClO4 perchloric acid

2, 3, 4, 5,6, 7 +7 HMnO4 permanganic acid

The following properties of elements are periodic: metallicity and the related reducing ability; ionization energy; nonmetallicity and related oxidizing ability; electron affinity; electronegativity; atomic radii. Properties having no periodicity are nuclear charge; atomic mass. 25

Questions and exercises on discipline «Inorganic Chemistry»

Example 1. Write the electronic formula of calcium and titanium atoms. To which family do they correspond? Solution. Calcium and titanium are elements of the IV period and their atoms have 4 electronic layer. In calcium (z = 20), the next element after argon (z = 18), 4s sublayer is filled by two electrons. Electron configuration of calcium is: 1s22s22p63s23p6…4s2. After filling of 4s sublevel electrons enter in the 3d sublevel and therefore the electronic formula of titanium (atomic number is 2 units higher than that of calcium) is: 1s22s22p63s23p63d24s2. Calcium is s-element, and titanium is d-element. 28. Fluorine: 1. Electronic configuration of atom is 1s22s22p5 2. p-element 3. Most electronegative element of the PS 4. Active reducing agent 5. Configuration of atom is 1s22s22p6 6. s-element 7. Low chemical activity 8. d-element 29. The majority of d-elements are characterized by: 1. Formation of nonstoichiometric compounds 2. Active role in biological systems 3. Amphoteric 4. Formation of only daltonides 5. Low complexing ability 6. Large size of atom 7. High chemical activity at normal temperature 8. Increasing of radius of atom from top to down by the subgroup 30. An element, which has no excited state is 1. Yttrium 26

The main chapters of the subject «Inorganic Chemistry»

2. 3. 4. 5. 6. 7. 8.

Hafnium Chromium Sodium Fluorine Aluminum Vanadium Lead

31. Characteristic features of d-elements: 1. Rich set of colored compounds 2. Complexation 3. Increasing of the stability of the compounds of higher oxidation states with increasing of charge of nucleus of atom 4. Most of compounds have no color (colorless) 5. Low ability to form complexes 6. Lowering of stability of compounds of higher oxidation states with increasing of charge of nucleus of atom 7. Absence of polyvalence 8. Increasing of radius of atom from top to down by subgroup 32. The sum of principal and orbital quantum numbers is the same value for… 1. 5s 2. 2р 3. 5p 4. 6s 5. 4s 6. 6p 7. 3s 8. 4d 33. Electronic configurations of the valence layer of atoms of iron, cobalt, nickel are … 1. 4s23d6 2. 4s23d7 3. 4s23d8 4. 4s23d3 5. 4s23d4 6. 4s13d6 7. 4s13d7 8. 4s23d9 27

Questions and exercises on discipline «Inorganic Chemistry»

34. In a series of elements of the sixth main group from top to down 1. Radius of atom increases 2. Metal properties increase 3. Stability of compounds of low positive oxidation states grows 4. Radius of atom decreases 5. Non-metallic properties increases 6. Stability of compounds of high oxidation states grows 7. Internal periodicity is characteristic for their compounds 8. Acidic properties increases 35. Electronic configuration of the valence layer of atoms of the elements of the subgroup of chromium 1. ns1(n-1)d5 (Cr) 2. ns1 (n-1)d5 (Mo) 3. ns2(n-1)d4 (W) 4. ns2(n-1)d4 (Mo) 5. ns2(n-1)d4 (Cr) 6. ns1 (n-1)d5 (W, Mo) 7. ns1 (n-1)d5 (W, Cr) 8. ns1 (n-1)d5 (W) 36. For halogens with increasing of atomic number … 1. Reducing capacity increases 2. Non-metallic properties weaken 3. Oxidation ability weakens 4. Radius of atom decreases 5. Non-metallic properties enhance 6. Oxidizing ability enhance 7. Naturally occurs in free state 8. Chemically inactive 37. Inert gases are found in: 1. Air 2. Natural gas 3. Minerals and mineral water sources 4. Only in air 5. Only in natural gases 6. Only in minerals 7. Only in waters of mineral springs 8. In regular water 28

The main chapters of the subject «Inorganic Chemistry»

38. Atoms or ions with 8-electron outer shell are … 1. С-4 2. K 3. N-3 4. V+5 5. Cs+ 6. P 7. Cl 8. Sc 39. The correct statement about the properties of metals 1. The oxidation state in compounds is only negative 2. In the main group from top to down metallic properties decrease 3. In the main group from top to down atomic radius decreases 4. Decreasing of ео меn+/ме, metallicity of element increases 5. The oxidation state in compounds is only positive 6. In the main group from top to down ionization energy does not change 7. In the main group from top to down reducing properties reduce 40. The chemical activity of simple substances of f-elements ... 1. Is very high 2. Quickly react with water 3. Is soluble by heating 4. React with acids - nonoxidants with releasing of hydrogen 5. Is insoluble by heating 6. React with strong bases 7. Do not fade in the air 8. React with strong bases 41. Atoms corresponding to electron configuration ns2(n-1)d3 are … 1. N 2. P 3. V 4. O 5. Nb 6. As 7. Ta 8. Bi 29

Questions and exercises on discipline «Inorganic Chemistry»

42. Electron configuration 1s22s22p63s23p6 can correspond to: 1. F2. Cl3. K+ 4. Mg2+ 5. Na+ 6. Fe2+ 7. Ar 43. The feature of the electronic structure of atoms of typical metals 1. High electron affinity 2. High ionization energy 3. Small atomic radius 4. Electronegativity is less than two 5. Number of electrons of outer layer of atoms is less than two 44. Atoms, corresponding to electron configuration ns2(n-1)d2, are… 1. N 2. P 3. Ti 4. O 5. Zr 6. As 7. Hf 8. Bi 45. For the elements of the second group of the main subgroup with increasing of atomic number 1. Ionization energy increases 2. Electronegativity increases 3. Reducing properties increase 4. Electron affinity decreases 5. Electronegativity decreases 6. Ionization energy decreases 7. Oxidative properties increase 46. Choose the correct statement of the periodic law in terms of modern science 1. The properties of simple substances, as well as the form of their compounds are in periodic dependence on their atomic masses 30

The main chapters of the subject «Inorganic Chemistry»

2. The properties of simple substances, as well as the form of their compounds are in periodic dependence on sum of atomic masses 3. The properties of simple substances, as well as the form of their compounds are in periodic dependence on charge of nuclei of their atoms 4. The properties of simple substances, as well as the form of their compounds are in periodic dependence on sum of charge of their atoms 5. There is no correct answer. 47. Choose the correct formulation of the basic principles of the theory of Planck 1. Light energy is absorbed and radiated continuously 2. Light energy is absorbed and emitted not continuously, but in separate indivisible portions – quanta 3. Light energy is not absorbed 4. Light energy is emitted continuously 5. There is no correct answer. 48. Choose the value of Planck's constant 1. h = 6.626∙10-27erg·sec 2. h = 0.1∙10-10 erg·sec 3. h = const 4. h > 1 5. There is no correct answer. 49. In a small period with increasing of atomic number of chemical element: 1. Atomic radius decrease 2. Electronegativity of atoms decrease 3. Atomic radius increase 4. Electronegativity of atoms increase 5. Atomic radii and electronegativity do not change 6. Non-metallic properties are enhanced 7. Reducing properties increase 8. Oxidizing properties decrease 50. Choose the correct formulation of the Rutherford model structure of the atom 1. The planetary model: there is a dense positively charged nucleus in the center and around the nucleus, at a distance exceeding the 31

Questions and exercises on discipline «Inorganic Chemistry»

2. 3. 4.

5.

size of the nucleus in the ~ 10,000 times, light negatively charged electrons are rotating The positive charge is spread across atom, a negative charge is interspersed therein The electrons are rotating on a steep orbit around the nucleus The electrons have a dual nature: a particle and a wave. Therefore, the atom has a wave nature and motion of the electron in it is determined by equation of standing wave There is no correct answer.

51. Choose correct definition of postulate of Bohr 1. Electrons do not rotate around the nucleus, electron cloud exists independently 2. Electrons rotate around the nucleus only in certain stationary orbit, being on which the electron loses or absorbs energy 3. Electron rotates only around its own axis 4. Electron rotates around nucleus by bohr's orbit and continuously absorbs energy 5. Electron rotates only around its own axis and continuously emits energy 52. Choose correct definition of the physical meaning of the square of wave function ǀΨǀ2 1. ǀΨǀ2 is atomic orbital 2. ǀΨǀ2 is the density of the electron cloud between nucleus and last electron 3. ǀΨǀ2 is the probability density of existing of electron in a particular region of space 4. ǀΨǀ2 is excited atomic orbital 5. ǀΨǀ2 is form of molecular orbital 53. The electron affinity is: 1. Energy needed to remove an electron from the unexcited atom 2. Ability of atoms of element to attract electron density 3. Energy released at joining of electron to atom 4. Energy absorbed at joining of electron to atom 5. Ability of atoms of element to shift an electronic density from itself 32

The main chapters of the subject «Inorganic Chemistry»

54. The ionization energy is: 1. Energy needed to remove an electron from unexcited atom 2. Ability of atoms of element to attract electron density 3. Energy released at joining of electron to atom 4. Energy absorbed at joining of electron to atom 5. Ability of atoms of element to shift an electronic density from itself 55. Choose the number of unpaired electrons in the ground state of an atom of iron: 1. 2 2. 4 3. 3 4. 7 5. 6 6. 1 7. 5 56. Choose correct definition of «principal quantum number» and «orbital quantum number» 1. Size of electron cloud 2. Energy level of electron in atom, which determines energy 3. Form of electron cloud 4. Magnetic state of electron in atom 5. Angular momentum 6. Determines spatial shape of orbital 7. Energy level 57. Choose the correct formulation of the Aufbau principle 1. At the same values of the sum (n+l) filling of orbitals occurs consistently in the direction of increasing of principal quantum number «n» 2. At the same values of the sum (n+m) filling of orbitals occurs consistently in the direction of increasing of principal quantum number «n» 3. First the orbital with less value of the principal quantum number «n» is filled 4. At the same values of the sum (n+s) filling of orbitals occurs consistently in the direction of increasing of principal quantum number «n» 33

Questions and exercises on discipline «Inorganic Chemistry»

5. The position of electrons in the periodic table corresponds to the electron structure of atoms 58. Choose correct definition of «magnetic quantum number» m 1. m is angular momentum 2. m is form of electron cloud 3. m is orientation of electron cloud in space 4. m is energy level 5. m is energy sublevel 59. Choose correct definition of «spin quantum number» S 1. S is one of excited atomic orbitals 

2. S is intrinsic magnetic moment 

3. S is result of rotation of electron around its own axis 4. S is projection of the magnetic quantum number on axis of movement 5. S is energy sublevel 60. Choose correct formulation of the Pauli principle 1. In atom can be several energy levels with the same quantum numbers 2. In atom cannot be two electrons with all four equal quantum numbers 3. In atom can be only two electrons with the same quantum numbers 4. In atom only at p sublevel can be electrons with the same quantum numbers 5. There is no correct answer. 61. Choose correct formulation of the «Hund's rule» 1. Total spin in the distribution of electron on energy level must be 0 2. Total spin in the distribution of electrons within the energy level should be minimal 3. Total spin in the distribution of electrons within the energy level should be maximized 4. Total spin must be > 1 5. Total spin must be 0 A = pΔV > 0 ΔU= Qp + A = Q- pΔ V ; Qp= ΔU – A = ΔU + pΔ V Qp= U2-U1 + p(V2 – V1) = ( U2 + pV2 ) – (U1 + pV1). Function U + pV = H is called enthalpy. So, U2 + pV2 and U1 + pV1 are values of enthalpies of states 2 and 1 of the system, respectively: U2 + pV2 = H2; U1 + pV1 = H1. Then Qp = H2 – H1 = ΔH. Heat attached to the system at a constant pressure is equal to the enthalpy change of the system. The change of enthalpy is the heat released in the isobaric process. Since the enthalpy shows from the internal energy, it is also a state function. It is measured and calculated not the enthalpy itself, but its change, shown in normal conditions: H2 – H1 = ΔH0298 kJ/mol. 70

The main chapters of the subject «Inorganic Chemistry»

Formation of substances may occur both with the absorption and releasing of energy. If the value of Qp is positive, the reaction is endothermic, i.e. enthalpy of reaction products is higher than enthalpy of the initial materials. If the value of Qp is negative, the reaction is exothermic, i.e. enthalpy of reaction products is lower than enthalpy of the initial materials. The enthalpy of simple substances is assumed to be zero (ΔH 0Cu∙ Δ ). The substance is stronger, if more energy is released during its formation. The change in enthalpy of a chemical reaction, i.e. thermal effect, obeys Hess’s law (1840). Hess’s law. Standard enthalpy of chemical reaction depends only on the initial and final state of the chemical reaction, i.e. depends on the type and state of the initial materials and reaction products. Consequence of Hess’s law. The change in enthalpy of a chemical reaction is the sum of enthalpy change of the reaction products minus the sum of the change of enthalpy of the starting materials: aA + bB = cC + dD ΔH 0chemical reaction= (cΔH 0C + dΔH 0D) – (aΔH 0A + bΔH 0B) kJ. Entropy The first law of thermodynamics tells us nothing about direction of process. About direction of process says second law of thermodynamics. The second law of thermodynamics: heat cannot move from a less heated body to a warmer body. Let us consider two tanks in an isolated system. As the energy transfer, hot tank cools and cold tank heats. Consequently, the temperature difference between tanks decreases during the whole period of realization of work. It means that the amount of 71

Questions and exercises on discipline «Inorganic Chemistry»

energy which can be spent on the work (it depends on the temperature difference) must decrease all time. The energy that has passed from the heat transfer to the heat exchanger and turned into a work is called fixed, or unavailable, energy, as it cannot turn to work.

To denote this fixed, or unavailable, energy Clausius introduced the following thermodynamic function which he called entropy S (transformation). Entropy is the ratio of heat to a temperature at which this energy transfer occurs S = Q/T, J/mol·K. The physical meaning of entropy is so complex that it was not explained for a long time. Boltzmann explained it. He called the entropy of the thermodynamic probability of the existence of the system, i.e., this macrostate system meets the set of microstates. The microstate of the system is speed and trajectory of each microparticle of the system, as well as the relative position of microparticles, number of collisions, etc. Entropy according to Boltzmann: S = K·lnW, where W is probability of the state of the system, K is Boltzmann constant. Entropy is a measure of disorder in a system. Absolute entropy is determined and calculated, normalized to normal conditions. All real systems have positive entropy. 72

The main chapters of the subject «Inorganic Chemistry»

C (diamond) – S0(c) = +2.38 J/mol·K. It resulted to the third law of thermodynamics. Perfect crystals at absolute zero have zero entropy. In real conditions in an isolated system the value is fixed, or unavailable, energy increases, i.e. spontaneously entropy can only increase. H2O(ice)→H2O(liquid)→H2O(steam) S01 < S02 < S03 This process takes place with increasing of entropy: ΔS0> 0, the reverse process characterizes as ΔS0 0 – irreversible process, ΔS0298 = 0 – reversible process. Since the entropy is a state function of system, i.e., depends on the initial and final states of the system, the change in the entropy of a chemical process depend on the type and condition of initial materials and reaction products. aA + bB = cC +dD; ΔS0chemical reaction= (cS0C + dS0D) – (aS0A + bS0B) J/K. For isolated systems entropy change allows us to predict whether the process is irreversible or reversible. If enthalpy change is zero, the process is reversible. These criteria cannot be used for closed systems. For closed systems new thermodynamic function – Gibbs energy (isobaric – isothermal potential) is introduced. Let us consider a closed system in which the process takes place at a constant temperature. According to the second law of thermodynamics, the following transformations are allowed: for reversible process: ΔS= Q/T; Qr =ΔS0T; Qr - ΔS0T= 0 ; ΔH0 -ΔS0T= 0; for irreversible process: ΔS> Q/T; ΔS0T> Q; Qr < ΔS0T; Qr-ΔS0T n = As a result: C 

рV . RT

pV p  . RT  V RT

Let’s express the value of Kc:

Kc 

 p NH 3     RT   p H2     RT 

3

2

 p N2    RT 





2 p NH

 

3  RT 3 pH  pN 2 2

312



2 p NH

3 3 pH  pN 2 2

Or you can write in the other way:

Kc 

2 p NH 3 pH

2

3

 pN 2

 n

 RT

initial

n final 

After minor transformations we obtain:

Кс  К р 

RT n

or 90

finsl

 ninitial



RT 2 .

The main chapters of the subject «Inorganic Chemistry»

К

р

 К

с

 n ,

 RT

where Δn is the difference in coefficients in the reaction equation

n  ( d  c )  ( а  в ) . For reactions occurring without volume change, we get: Кс  К р .

There is a relationship between the change in the isobaric-isothermal potential of a chemical reaction and the equilibrium constant expressed in terms of the partial pressure of the components A, B, C, D, E in equilibrium. For 298ºK temperature it is as follows: 0 G298   RT  ln K p .

The direction of shifting of chemical equilibrium position as a result of changing in external conditions is defined by Le Chatelier's principle: when any system at equilibrium is subjected to change in any conditions then the system readjusts itself to counteract the effect of the applied change. Effect of concentrations of reactants on equilibrium. In the contact process of production of H2SO4 the oxidation of SO2 in SO3 at the presence of a catalyst (Pt or V2O5) follows by the equation:

2SO2  O2   2SO3 If in this equilibrium system to add extra O2, the system amplifies the process that leads to reduce the O2 concentration. Such process is 91

Questions and exercises on discipline «Inorganic Chemistry»

the direct reaction of SO2 with O2 to form SO3. Thus, the system will shift the equilibrium toward the formation of SO3. The same conclusion can be obtained as a result of the analysis of the expression of the equilibrium constant:

      2

SO

Кс 

3 2

SO 2

 O2

With increasing of concentration of O2 (denominator in this expression) the concentration of SO3 (numerator) should increase. This follows from the fact, that KC = const. Thus, increasing of the concentration of O2 will move the balance to a fuller usage of SO2, and a greater yield of SO3. Effect of pressure on equilibrium. Pressure is essential in the reactions between gases. As a result of increasing of pressure, the concentration of the reactants and thus the reaction rate increase. Let us consider the possible cases. a. In reaction sum of the moles of the initial substances is the sum of moles of reaction products. The total volume of the corresponding gases will also be equal. N 2  O2   2 NO If the pressure increases in a closed reaction vessel 2 times, then the volume change is also doubled. Accordingly, the gas concentration will change 2 times. The rate of direct and reverse reactions increases, but an equal number of times. Therefore, displacement of chemical equilibrium does not happen. ' vdirect  k direct 2 N 2   2O2   4k direct N 2 O2   4vdirect   '  2 2 vreverse  k reverse 2 NO  4k reverse NO  4vreverse 

Thus, if the initial and final volumes of the gaseous products of the equilibrium of the system are equal, then the pressure change does not disturb the balance. 92

The main chapters of the subject «Inorganic Chemistry»

b. The amount of moles of initial substances is larger than the sum of moles of formed products: N2 + 3H2  2NH3. From four moles of initial substances two moles of products forms, i.e. the reaction proceeds with decreasing in volume. At the increasing of pressure, the concentration of the initial substances will increase to a greater extent than the concentration of the products, leading to a shift in the equilibrium towards the formation of ammonia.

c. The sum of moles of the initial substances is less than the sum of the moles of products: N2O4 ↔2NO2;

Direct reaction leads to increasing of the number of moles of substances in the system, that is, to increasing of the pressure. In a reversible reaction, on the contrary, the system pressure falls. If at established balance to increase the pressure, the system will show counteraction in an effort to the initial state. The equilibrium will shift toward the reverse reaction, accompanied by decreasing in pressure, i.e. towards the formation of N2O4. If to decrease pressure, the equilibrium shifts toward the reverse reaction, accompanied by increasing of pressure, i.e. in the direction of NO2 formation. Effect of temperature on equilibrium. When heating system in equilibrium, the equilibrium shifts toward the endothermic reaction, when cooling it shifts in the direction of an exothermic reaction. Effect of catalyst on equilibrium. The introduction of catalysts in the equilibrium system does not cause displacement of equilibrium as a catalyst accelerates both 93

Questions and exercises on discipline «Inorganic Chemistry»

direct and reverse reactions. But the introduction of catalysts allows us to achieve the balance in a shorter time. Example 1. The constant equilibrium H2 + I2

2HI

at any temperature is equal to 40. Determine what percentage of hydrogen and iodine will transfer to HI. The initial concentrations of these substances are the same and equal to 0.01 mol/l. Solution. Let us express the equilibrium concentrations of substances through the initial. For this let us denote decreasing of the concentration of hydrogen and iodine at the time of equilibrium in terms of x. Consequently, equilibrium concentrations are [I2]=(0.01- ) mol/l, [H2]=(0.01- ) mol/l, [HI]=2 mol/l. To determine x let us substitute the numerical values of the equilibrium concentrations in the equilibrium constant expression:

The equation has two roots: 1=0,0146 и 1=0,0076. From two values of x, select that one which corresponds to conditions of the task. Initial concentrations of hydrogen and iodine are equal to 0.01 mol/l. Consequently, x cannot have a value greater than 0.01 and the solution has one root, equal to 0.0076 mol/l. Thus, from 0.01 mole of hydrogen and 0.01 moles of iodine, per 0.0076 moles reacted, which is equal to

162. The process of obtaining of ammonia from nitrogen-hydrogen mixture is … 1. Reversible 2. Exothermic 3. Heterogeneous catalytic 94

The main chapters of the subject «Inorganic Chemistry»

4. 5. 6. 7. 8.

Irreversible Endothermic Homogeneous-catalytic Not catalytic Proceed at ordinary temperature

163. Which factors positively affect on the yield of ammonia in the reaction N2 + 3H2 2NH3 + Q 1. Only temperature 2. Only pressure 3. Only increasing of concentration of nitrogen 4. Temperature 5. Outside factors do not affect on this reaction 6. Pressure 7. Catalyst 8. Stirring 164. All industrial installations of ammonia synthesis work using the principle of circulation, i.e. … 1. After reaction, mixture of gases is heated 2. After reaction, mixture of gases is cooled 3. Containing in a mixture ammonia gas is condensed and separated 4. Unreacted nitrogen and hydrogen are mixed with fresh portion of gases and again are supplied to catalyst 5. Containing in mixture ammonia gas is only condensed 6. Unreacted nitrogen and hydrogen are again supplied to catalyst 7. Only containing in mixture ammonia gas is separated 8. Containing in mixture ammonia gas is given in separate container 165. The reaction N2 + 3H2 ↔ 2NH3 + 92 kJ(cat.) can be referred to reactions: 1. Combination 2. Irreversible 3. Exothermic 4. Endothermic 5. Catalytic 6. Reversible 7. Hydration 8. Neutralization 95

Questions and exercises on discipline «Inorganic Chemistry»

166. The reaction (NH4)2Cr2O7 → N2 + Cr2O3 + H2O can be referred to reactions: 1. Decomposition 2. Irreversible 3. Exothermic 4. Redox 5. Catalytic 6. Hydrogenation 7. Hydration 8. Neutralization 167. Which of the following reactions is irreversible? 1. H2 + Cl2 = 2HCl 2. Mg + O2 = MgO 3. 2H2 + O2 = 2H2O 4. N2 + 3H2 = 2NH3 5. H2 + Cl2 = 2HCl 6. Zn + 2HCl = ZnCl2 168. Select the definition of rate of chemical reaction 1. Change in concentration of reactants per time unit 2. Proportionality factor between concentrations of substances 3. Constant determining changing in concentration of one of reactants 4. Constant determining dependence of reaction mechanism from time 5. There is no correct answer. 169. Select the definition of rate constant 1. Dependence determines change in rate of reaction 2. Coefficient of proportionality between rate of reaction and con[ A]

centrations of reactants in rate equation v  K [ B]

3. Relationship between speed of chemical reaction 4. Constant characterizing dependence of rate from temperature 5. There is no correct answer. 170. Select factors, influencing on rate of chemical reaction 1. Time 96

The main chapters of the subject «Inorganic Chemistry»

2. 3. 4. 5. 6. 7.

Concentration of substances Temperature Catalyst Rate of chemical reaction doesn’t depend on external factors. Acidity There is no correct answer.

171. Determine the order of the reaction in the equation A + B → products. v = K [A] [B] 1. 1st order 2. 2nd order 3. Zero order 4. Such reactions have no order 5. 3rd order 172. Choose the correct formulation of the law of action mass 1. Ratio of concentration of reactants and products at equilibrium is constant 2. Concentration of reactants increases monotonously 3. Concentration of reactants decreases monotonously 4. Concentration of reactants does not change 5. There is no correct answer. 173. Select the correct formulation of the concept «chemical equilibrium» 1. Status of chemical system in which rate of reverse reaction is less than rate of direct reaction 2. Status of chemical system in which rate of direct reaction is less than rate of reverse reaction 3. Status of chemical system in which rate of reverse reaction is zero 4. Status of chemical system in which rate of direct reaction is equal to zero 5. Status of chemical system in which rate of formation of products is equal to rate of direct reaction 174. Select the correct definition of activation energy 1. Maximum energy which reagents should receive in a chemical reaction 97

Questions and exercises on discipline «Inorganic Chemistry»

2. Minimum energy which reagents should receive in a chemical reaction to overcome the barrier preventing formation of products 3. Maximum energy required to overcome forces of attraction between molecules 4. Minimum energy required for separation of molecules by dipoledipole interaction 5. There is no correct answer. 175. Catalyst accelerates a chemical reaction due to: 1. Reducing of activation energy 2. Increasing of activation energy 3. Increasing of randomness of molecular motion 4. Increasing of collisions of molecules 5. Increasing of energy of hydration 176. Accelerating role of catalyst is explained by: 1. Formation of activated transition complexes 2. Increasing of chaotic motion of molecules 3. Increasing of number of collisions of molecules 4. Increasing of energy of hydration 5. Increasing of kinetic energy 177. Which factors most completely influence on rate of chemical reaction? 1. Nature of reactants, pressure, concentration 2. Catalyst, crushing, concentration 3. Nature of reactants, concentration, temperature, catalyst 4. Pressure, grinding, heating 5. Cooling, catalyst, pressure 178. For which reaction increasing of pressure and lowering of temperature shift the balance to right of reaction? 1. CO + H2O ↔ CO2 + H2 + Q 2. 2CO + O2 ↔ 2CO2 + Q 3. N2 + O2 ↔ 2NO – Q 4. Ss + O2 ↔SO2 + Q 5. 2HBr ↔ H2 + Br2 – Q 179. For which reaction increasing of temperature and lowering of pressure shift the balance to left of reaction? 1. N2 + O2 ↔ 2NO – Q 98

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2. 3. 4. 5.

2NO +Cl2 ↔ 2NOCl + Q N2 + O2 ↔ 2 NO – Q CO2 + C ↔2 CO + Q H2 + Cl2 ↔ 2HCl + Q

180. Which factors contribute to a shift of reaction to left: 2SO2 + O2 → 2SO3 + Q? 1. Increasing of SO2 concentration 2. Increasing of temperature 3. Increasing of pressure 4. Increasing of SO3 concentration 5. Decreasing of temperature 6. Decreasing of O2 concentration 7. Increasing of O2 concentration 8. Decreasing of SO3 concentration 181. Reaction А2 (g) + В2 (g) = 2АВ (g) flows in a gas phase as molecular collisions A2 and B2. Doubling of concentration of each of reactants keeping all other conditions without changing, the reaction rate will increase: 1. 2 times 2. 4 times 3. rate of reaction will not change 4. 3 times 5. 6 times 182. How many times will increase the rate of reaction 2NO + O2 = = 2NO2, if to increase concentration of nitric oxide (II) 2 times? 1. 2 times 2. 4 times 3. 6 times 4. 8 times 5. 7 times 183. Increasing of the concentration of chlorine three times in the reaction – H2 + Cl2  2HCl - leads to: 1. Increasing of reaction rate 3 times 2. Decreasing of reaction rate 3 times 3. Decreasing of reaction rate 6 times 99

Questions and exercises on discipline «Inorganic Chemistry»

4. Increasing of reaction rate 6 times 5. Increasing of reaction rate 9 times 184. Determine the correct record of depending on the speed of the direct reaction on the concentration for the chemical reaction: 3M + 2N + P = J, occurring in gaseous phase? 1. V1  k1  C 2M  C p ; 2. V1  k1  C N  Cp ; 3. V1  k1  CM  C2N ; 4. V1  k1  C2M  C N ; 5. V1  k1  C3M  C 2N  C p . 185. Write equation of dependence of rate on concentration for the chemical reaction: 2A + B + D = F, which occurs in gaseous medium. 1. V1  k1  C2A  CB  CD ; 2. V1  k1  CA  CB  CD ; 3. V1  k1  C A  CB ; 4. V1  k1  C A  C2D ; 5. V1  k1  C 2A  CD 186. The reaction is carried out as molecular collisions A + A + B + + B + C = D Identify expression of rate of direct reaction: 1. V1=k1[A][B] 2. V1=k1[A]2[B] 3. V1=k1[A]2[C] 4. V1=k1[A][B]2[C] 5. V1= k1[A]2[B]2[C] 187. The correct expression of the equilibrium of constant of reaction 3H2 + N2 = 2NH3 is: [ NH 3 ] 1. K  [H 2 ][N 2 ] 2 2. K  [ NH 3 ] [H 2 ][N 2 ]

100

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3. K 

[ NH 3 ]2 [H 2 ]3 [ N 2 ]

4. K 

[ NH 3 ]2 [H 2 ]6 [ N 2 ]2

5. K 

[ NH 3 ] [H 2 ]3 [ N 2 ]

188. The correct record of constant of chemical equilibrium for the reaction: 3Fe(s) + 4Н2О  Fe3O4(s) + 4Н2 is following:

 

1. К  р

2 2

4 4

Fe   (s)

2. К  р

2

4

Fe O    3

4( s )

2

4( s )

2

4

Fe O  H  Fe  H O

4

3

3. К  р

4

(s)

2

Fe 

4. К  р

(s)

Fe3O4 

5. К р  Fe3O 4  H 2 4 189. Constant of chemical equilibrium of the reaction 2Fe( s )  3Cl2( g )  2FeCl3( s ) is: 1. К  р 2. К  р

FeCl3 2 Fe2 Cl 2 3

2FeCl3  2Fe 3Cl 2 

3. K P  Cl 2 3 4. K P  FeCl3 





2 5. К  Fe] [Cl 2 р FeCl3 2

3

101

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190. How will the speed of direct reaction 2SO 2(g) + O2(g) 2SO3(g) change, when the pressure increases 3 times at constant temperature? 1. Increases 3 times 2. Does not change 3. Decreases 27 times 4. Increases 27 times 5. Increases 6 times 191. The temperature coefficient is equal to 2. To increase the rate 16 times it is necessary to raise temperature by: 1. 40 °С 2. 4 °С 3. 256 °С 4. 20 °С 5. 80 °С 192. When the concentration of the reagents in the system: 

2NO(g) + O2(g)   2NO2(g) increases 2 times, the rate of reaction:  1. Increases 2 times 2. Does not change 3. Increases 8 times 4. Decreases 8 times 5. Increases 6 times 193. The equilibrium in the system shifts to the right with increasing of pressure in the reaction: 1. 2H2O → 2H2(g) +O2(g) 2. N2(g) + 3 H2(g) → 2NH3(g) 3. CaCO3(cr.) → СaO(cr.) + СO2 (g) 4. СO(g) + H2O(g) → СO2(g) + H2(g) 5. H2(g) + Cl2(g) → 2HCl(g) 194. The equilibrium of reaction Fe3O4(s) + 4CO(g) - 43,7 kJ shifts to reactants by: 1. Decreasing of temperature 2. Increasing of co concentration 3. Increasing of temperature 4. Reducing of pressure 5. Increasing of pressure 102

3FeO(s) + 4CO2(g) -

The main chapters of the subject «Inorganic Chemistry»

6. Increasing of co2 concentration 7. Including of catalyst 195. The equilibrium of reaction 2CO(g) + O2(g) 2CO2(g) +Q shifts to products of reaction: 1. Increasing of pressure 2. Decreasing of temperature 3. Increasing of temperature 4. Decreasing of pressure 5. Increasing of co concentration 6. Including of catalyst 7. Decreasing of pressure 8. Increasing of concentration of carbon dioxide 196. The system 2CO2(g) 2CO(g) + O2(g) H 0298 = 134,000 kJ is in a balance. In which direction will shift the equilibrium, when temperature increases? 1. Will not displace 2. Right 3. Left 4. To exothermic reaction 5. To endothermic reaction 197. In which direction will shift the equilibrium in the system N 2(g)+ +O2(g) = 2NO(g) H 0298 = 43,200 kJ, when temperature decreases? 1. Will not displace 2. Right 3. To exothermic reaction 4. Left 5. To endothermic reaction 6. Reaction occurs spontaneously 198. Select factor influencing on shifting of equilibrium to right in reaction С2H4(g) + 3O2(g) =2CO2(g) + 2H2(g) H 0298 = -1323 kJ: 1. Entropy factor 2. Decreasing of temperature 3. Increasing of concentration of hydrogen 4. Increasing of concentration of carbon dioxide 103

Questions and exercises on discipline «Inorganic Chemistry»

5. Decreasing of concentration of carbon dioxide 6. Increasing of pressure 199. Which factor leads to a change of rate constant? 1. Changing of pressure 2. Changing of temperature 3. Changing of volume of reaction vessel 4. Changing of concentration of products of reaction 5. Changing of concentration of reactants 200. How will the rate of direct reaction СO2+Сs ↔ 2СO change, if to increase concentration 2 times? 1. Will increase 2 times 2. Will increase 4 times 3. Will decrease 2 times 4. Will not change 5. Will decrease 4 times. 201. How will the rate of formation of NH 3 from hydrogen and nitrogen change, if to increase concentration 2 times? 1. Will increase 2 times 2. Will decrease 2 times 3. Will decrease 16 times 4. Will increase 4 times 5. Will not change 202. How will the rate of reaction 2SO 2+O2  2SO3 change, if to decrease pressure of the system 3 times? 1. Will increase 9 times 2. Will decrease 9 times 3. Will not change 4. Will decrease 900·10-2 times 5. Will increase 27 times 6. Will decrease 0.009·102 times 7. Will decrease 27 times 8. Will decrease 0.0027·102 times 203. How will the rate of chemical reaction change if to increase temperature from 1400 °C to 1600 °C, if the temperature coefficient is equal to 4? 1. Will increase 4 times 2. Will increase 16 times 104

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3. Will increase 16 times 4. Will increase 4 times 5. Will not change 204. How will the rate of chemical reaction change if to decrease temperature from 100 °C to 70 °C, if the temperature coefficient is equal to 3? 1. Will increase 3 times 2. Will decrease 27 times 3. Will decrease 3 times 4. Will increase 27 times 5. Will increase 9 times 205. How is it necessary to change temperature and pressure in the system: 2CH4(g) + О2(g) 2СО2(g) + 4Н2(g) - Q, in order to improve the yield of hydrogen? 1. To reduce temperature and to increase pressure 2. To increase temperature and to increase pressure 3. To increase temperature and to decrease pressure 4. To decrease temperature and to decrease pressure 5. To increase temperature, do not change pressure 206. Select the correct expression of the law of mass action for rate of direct reaction of system HIg + CH3Ig  CH4g + I2s 1. V = k CH4  I2 2. V = k HI  CH3I 3. V = k HI 4. V = k CH4 5. V = k CH3I.

8. General properties of solutions The solution is called a solid or liquid homogeneous (uniform) system consisting of two or more components. The essential components of the solution are solvent and solute, for example, sugar dissolved in water. Several solutes can be in one solvent. For example, sugar, salt and acetic acid are dissolved in water. 105

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The amount of solute in a solution or a certain amount of solvent (which can vary in a very wide range) is called the concentration of the solution. There are several ways to express the concentration of solutions. 1. Mass concentration (P) is the solute expressed in gram contained in 100 grams of solution:

where: х is mass of solute in grams; y is mass of solvent in grams; (x + y) is mass of solution in grams. The weight of the solution can be expressed by the product of the density of the solution on its volume: x+y=ρ·V hence

For example, a 5% solution means 5 g (x) is contained in 100 g of (x + y) or 5 g (x) contained in 95 g of (y). 2. Molar concentration (CM) is the number of moles of a solute in 1 dm3 of solution:

where: CM is molar concentration in mol/dm3; х is mass of solute in grams; M is molar mass of solute in g/mol, V is volume in dm3. For example, 0.2M HCl means that 0.2 mole of HCl was dissolved in 1 dm3 of solution. 3. Equivalent (normal) concentration (Ceq or CN) is the number of moles of equivalents of solute in 1 dm3 of solution:

106

The main chapters of the subject «Inorganic Chemistry»

where: CN is normal concentration in mol/dm3; х is mass of solute in grams; M is molar mass of equivalent of solute in g/mol; V is volume in dm3. For example, 0.5N H2SO4 means that 0.5 mol of equivalents of sulfuric acid is contained in 1 dm3 of solution. Equivalent of element is amount of it connected with one mole of hydrogen atoms or replaces the same number of hydrogen atoms in chemical reactions. For example, in НСl, H2S, NH3 compounds equivalents of chlorine, nitrogen and sulfur are, respectively, 1 mol, 1/2 mol, 1/3 mol. 4. Molal concentration (CM) is the number of moles of solute in kg of solvent.

where: CM is molal concentration in mol/kg; х is mass of solute in grams; M is molar mass of solute in g/mol, m is mass of solvent in kg. 5. Titer of the solution (T) is the solute expressed in grams in 1 cm3 of solution:

where: T is titer in g/cm3; х is mass of solute in grams; V is volume in cm3. The law of equivalents. If two solutions interact with each other in equivalent amounts, then, knowing the concentration of one of the solutions and the volumes of both reacted solutions, we can calculate the unknown concentration of the second solution by the equation: Ceq 1·V1= Ceq 2·V2 The basic laws of solutions. The basic laws of solutions are the laws of Raoult and Van't-Hoff. These laws are collegiate, i.e. they depend not only on the concentration of solutions, but also on the number of particles in them. 107

Questions and exercises on discipline «Inorganic Chemistry»

Lowering of saturated vapor pressure above the solution (the first law of Raoul) Any liquid evaporates: H2O(liquid)↔H2O(vapor) The vapor pressure in equilibrium is called the saturated vapor pressure. At this temperature the vapor pressure of each liquid is constant. Let us denote it as PA. Let us assume that any liquid can be a solvent. Any solute (solid) theoretically also evaporates and hence has a saturated vapor pressure. Let us denote it as PB. If solid substance is non-volatile, its saturated vapor pressure is almost zero. If the solution consists of two liquids, the solvent is the liquid, at which the vapor pressure is higher. Hence PA> PB is always true. Saturated vapor pressure (P) is the sum of the partial pressures of its components: 1. P = РА NА + РB NB, where: NА and NB are mole fractions of the solvent and solute, respectively. If the dissolved substance is solid, non-volatile, which has B = 0, then the expression РB·NB is also zero. Consequently: 2. P = РА·NА. For a two-component solution: 3. NА+ NB = 1. 4. Let us assume: NА = 1- NB. Let us transform the expression (2): P – РА = - РА·NB. As can be seen from the above that P< РА, then both sides of this equation have the sign (-). To get rid of the minus, let us multiply both sides by (-1) and we will get: РА – P = РА·NB. 5. ΔP = РАNB. ΔP value is the absolute decreasing of saturated vapor pressure above the solution compared with solvent. In chemistry a relative decrease in the saturated vapor pressure above the solution, which is equal to the mole fraction of solute, is accepted: 6. ΔP / РА = NB. 108

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Boiling and freezing of solutions (the second law of Raoul) The second law of Raoul defines change of the boiling and freezing points of solutions in comparison with the pure solvents. The solvent boils at a temperature at which its vapor pressure reaches atmospheric pressure: H2O(liquid)↔H2O(vapor) The solution boils at higher temperature as the concentration of the solvent molecules in it is always lower than the pure solvent, and a saturated vapor pressure of solution reaches atmospheric pressure at higher temperatures. The freezing point (crystallisation) of the solution is below the freezing point of the pure solvent. This is due to the lower pressure of the solvent vapor above the solution than the above solvent. The second law of Raoul determines what change of the boiling and freezing points of solutions is equal to. Changing of the boiling point and freezing point of solutions is proportional to molal concentration of solutions. Δt0boiling = Kb·См, Δt0freezing = Kf·См. Let us consider coefficients of proportionality: Kb is ebullioscopic constant, Kf is cryoscopic constant. Each solvent has its own values of Kb and Kf. Ebullioscopic and cryoscopic constants of some solvents are presented in the following table. Solvent H2O C6H6

Kb 0.53 2.57

Kf 1.86 5.02

Conclusion: changing of the boiling and freezing points of solutions depends on the nature of solvent and concentration of the solution. 109

Questions and exercises on discipline «Inorganic Chemistry»

The physical meaning of these constants is that at the solution concentration equal to 1 mol/kg, these constants are equal to change of boiling or freezing point temperature of the solution. Unlike pure solvents which boil and freeze at a constant temperature, the solutions boil and freeze in a temperature interval. The Law of Van't-Hoff determines the value of the osmotic pressure of the solution. To view the concept of osmosis, let us consider the vessel divided into two parts by a semipermeable membrane. The semipermeable membrane is the partition through which solvent molecules penetrate but do not pass the solute particles. Osmosis is the spontaneous on side movement of solvent molecules across a semipermeable membrane from the part of the system, where the solvent concentration is higher, in that part of the system, where its concentration is lower. Determination of the osmotic pressure of the solution is made as follows. The outer vessel is filled with pure water; the walls of the inner vessel are semi-permeable membrane. The inner vessel contains extended neck and a measuring ruler. The inner vessel contains a solution, such as sugar. Due to osmosis of water molecules from an external vessel through the semipermeable wall will take place in the inner vessel, the movement of molecules in this device only one-sided. Thus, the volume of solution in the internal vessel increases and rises through the neck. As a result of the difference in the level of the liquid in the external and internal vessels, hydrostatic pressure occurs in the device. This pressure prevents osmosis. The value of the hydrostatic pressure, at which the osmosis stops, is called the osmotic pressure of the solution (Π, kPa): Π = RTCB, kPa, where: R is universal gas constant, equal to 8.31 J/mol, T is absolute temperature, K, CB is molar concentration of solution. 110

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Example 1. There is 10% solution of sulfuric acid. The density of this solution is equal to 1.075 g/cm3. Calculate molal, molar concentration, equivalent (normal) concentration and titer of the solution. Solution. Let us calculate the molal concentration.

Let us calculate the molar concentration. To do this, let us choose an arbitrary volume of the solution. If V = 1 dm3, then: x+m=ρ·V=1.075·1000=1075 g x=1075·10%=107.5 g Hence

Let us calculate the equivalent (normal) concentration.

Let us calculate the titer of the solution

Example 2. In 450 g of water 50 g of CuSO4.5Н2О was dissolved. Calculate the percentage concentration of crystalline hydrate and anhydrous salt. Solution. The total mass of the solution is 500, the percentage of crystalline hydrate we can find out by proportion: 500 g of solution – 100 % 50 g of dissolved substance – х % 111

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The percentage concentration of anhydrous salt CuSO4 is:

where: 31.96 is the number of grams of CuSO4, corresponding to 50 g of CuSO4.5Н2О. Example 3. How many liters of 0.1 N AgNO3 solution is it necessary for the exchange reaction with 0.5 liters of 0.3N solution of AlCl3? Solution. There is 0.5.0.3=0.15 equiv. of AlCl3 in 0.5 l of 0.3 N solution of AlCl3. To interact with a given amount of AlCl3 the same number of equivalents of AgNO3, i.e. 0.15, is required. In 1 l of AgNO3 solution contains 0.1 eq, and 0.15 eq is contained in 1.5 liters of solution. The same result we get, using the formula

207. Which constant (x) is missing in the equation: Δt(cooling) =х·m? 1. Cryoscopic constant 2. Ebullioscopic constant 3. Equilibrium constant 4. Speed constant 5. Temperature 273°K 208. Which constant (x) is missing in the equation: Δt(boiling) =х·m? 1. Cryoscopic constant 2. Ebullioscopic constant 3. Equilibrium constant 4. Speed constant 5. Temperature 273°K 112

The main chapters of the subject «Inorganic Chemistry»

209. Select the correct determination of the solubility product of salt 1. Multiplication of ion concentrations in brine 2. Multiplication of ion concentrations in unsaturated salt solution 3. Multiplication of powers corresponding to stoichiometry of molecule of salt 4. Salt solubility under these conditions 5. Multiplication of concentrations of ions in brine, raised to powers corresponding to stoichiometry of molecule of salt 210. At 0°C KH2O= 1.14·10-15. Find the value of pKH2O at 0°C. 1. 13.1 2. 15.0 3. 17.1 4. 8.55 5. 30.0 . 211. At 0°С KН2О=1.14 10-15. Find the value of pH at 0°C of solution, containing 0.01 mol·dm-3 of NaOH. 1. 13.82 2. 14.82 3. 17.82 4. 7.41 5. 22.23 212. Which solution is called saturated? 1. A solution in which concentration of solute corresponds to its solubility at a given temperature 2. A solution with lower concentration of solute than its solubility at a given temperature 3. A solution with higher concentration of solute than its solubility at a given temperature 4. A solution in which 1 g-mole of substance is dissolved 5. A solution in which 2 g-mole of substance is dissolved 213. The water of crystallization is 1. Crystal compound dissolved in water 2. Hydration water, fixedly included in crystals, e.g., cuso 4·5h2o 3. Complex compound, dissolved in water 4. Water formed hydrate shell of salt 5. There is no correct answer. 113

Questions and exercises on discipline «Inorganic Chemistry»

214. Name of scientist-initiator of the physical theory of solutions is… 1. Lomonosov 2. Mendeleyev 3. Berthelot 4. Lavoisier 5. Arrhenius 215. Choose the correct formulation of the law of Henry 1. Product of pressure and volume is constant PV = const 2. Ratio of concentrations of dissolved substance in two immiscible liquids is constant K = 3. Solubility of gas in liquid is proportional to the gas pressure above the solution C= к·Р 4. In dilute solutions of electrolytes, lowering of vapor pressure of solvent is equal to mole fraction of solute 5. There is no correct answer. 216. What is the correct formulation of the concept «heat of solution» 1. Thermal effect of destruction of crystal lattice by dissolving of substance 2. ΔН·Т during dissolving 3. ΔS·Т during dissolving 4. Thermal effect of dissolution, referred to certain amount of solute 5. There is no correct answer. 217. In what cases the substance may be dissolved spontaneously? 1. ΔH > 0 2. ΔS < 0 3. ΔН·Т=const 4. ΔG =ΔН - TΔS, ΔG < 0 5. ΔG > 0 218. Select the definition «mole fraction» 1. Ratio of percentage content of one component to 100 g of solution 2. Ratio of g-mol of solute to solvent 3. Ratio of number of moles of one component of solution to total number of moles of all substances presented in solution 4. Ratio of % concentration to 100 ml of solution 5. Ratio of moles of solute to 1 liter of solution 114

The main chapters of the subject «Inorganic Chemistry»

219. Select the definition «normality of solution» 1. Number of moles of substance in 1 liter of solution 2. Number of g-mol of substance in 100 g of solution 3. Concentration of solution, expressed as number of equivalents of substance dissolved in 1 liter of solution 4. Concentration of solution, expressed in moles of substance in 1 liter of solvent 5. Concentration of solution, expressed in certain mole fractions of substances in 1 liter of solution 220. The laws of ideal solutions: 1. Lavoisier-Laplace 2. Konovalov 3. Van't Hoff 4. Henry 5. Hess 6. Avogadro 221. Crystal hydrates… 1. Absorb water 2. Interact with H2O 3. Release water 4. Contain crystallization water in composition 5. Products of reaction of particles of solute between themselves 6. Absorb crystallization water 222. Select correct definition of «percentage concentration of solution» 1. Number of equivalents of solute per 100 g of solution 2. Number of grams of substance dissolved in 100 g solution 3. Number of moles of substance dissolved in 100 g solution 4. Number of equivalents of substance dissolved in 1,000 g of solution 5. Number of moles of substance dissolved in 1,000 g of solution 223. Select correct definition of «molality of solution» 1. Number of mole fractions of substance in 1 liter of solution 2. Number of moles of substance in 1 liter of solution 3. Number of moles of substance dissolved in 1 kg of solvent 4. Number of grams of substance dissolved in 100 g of solution 5. Number of equivalents of substance dissolved in 1 liter of solution 115

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224. Select definition of «osmosis» 1. Movement of solvent molecules in solution 2. Phenomenon of unilateral diffusion through semipermeable membrane 3. Phenomenon of double-sided diffusion of solute molecules through a semipermeable membrane 4. Brownian movement of molecules in solution 5. There is no correct answer. 225. The osmotic pressure is… 1. Partial pressure above solution 2. External pressure 3. Intramolecular pressure of solute 4. Pressure required to solution to stop phenomenon of osmosis 5. Pressure required to increase process of osmosis 226. Select the correct formula of equation that determines the osmotic pressure 1. PΔV= mΔPΔT 2. P = iΔRΔT 3. Р = cΔRΔT 4. P0ΔV0 = PΔV 5. 227. Select the correct mathematical record of the 1 st Raoult's law 1. PV=mRT 2. V=m/c M

3. 4.

m RT p

(N is mole fraction of solute)

5.  Tboil = E·m 228. Select the correct wording of the 2 nd Raoult's law 1. Increasing of the boiling temperature and lowering of the freezing point of solution is directly proportional to molal concentration of solute; 2. Lowering of the boiling point and freezing point of solution is directly proportional to molal concentration of solute; 116

The main chapters of the subject «Inorganic Chemistry»

3. Freezing and boiling point of solution depends on concentration of solute; 4. Lowering of boiling point and freezing point of solution is inversely proportional to molal concentration of solute; 5. There is no correct answer. 229. What is the concentration of hydrogen ions and hydroxyl groups in pure water? + 1. [Н ] > [ОН ] 2. + [Н ] = [ОН ] = 10-7 + 3. [Н ] < [ОН ] 4. + [Н ] = 10-8 5. [ОН ] = 10-11 230. Which factors influence on solubility of substance? 1. Pressure 2. Temperature 3. Nature and properties of solute, temperature and pressure 4. Mixing 5. There is no correct answer. 231. Which factors increase solubility of gas in liquid? 1. Increasing of temperature at constant pressure 2. Decreasing of temperature at increasing of pressure 3. Increasing of pressure at constant temperature 4. Decreasing of pressure and increasing of temperature 5. There is no correct answer. 232. Select changing of values ΔH and ΔS during dissolving of substances. 1. ΔS>0; ΔН>0 2. ΔS=0; ΔН=0 3. ΔS=0; ΔН>0 4. ΔS>0; ΔН< 0 5. ΔS=0; ΔН< 0 117

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233. In which solvents do polar substances well dissolve? 1. Benzene 2. Carbon disulfide 3. Carbon tetrachloride 4. Liquid ammonia 5. Chloroform 234. Which of the following ions should be most strongly hydrated in an aqueous solution? 1. Li+ 2. K+ 3. Ca+2 4. Fe+3 5. V+5 235. What is % concentration of solution of salt, if 100 g of solution contains 5 g of NaCl? 1. 95% 2. 10% 3. 5% 4. 15% 5. 20% 236. Which ratio exists between vapor pressure above the solution (P) of non-volatile matter and mole fraction of solvent in solution (x)? 1. Р = х·Р0, where: Р0 is vapor pressure of pure solvent 2. Р = Р0 3. Р = const 4. P = heat of dissolution 5. Р = V·Р0 (V is volume) 237. Select value of pH of solution of NaHPO 4 1. pH = 7 2. pH > 7 3. pH < 7 4. pH ≥14 5. pH