Physical chemistry theory. Chemistry physical
PHYSICAL, the science of the general laws that determine the structure and chem. turning into at different ext. conditions. Researching chem. phenomena with the help of theoretical and experiment. methods of physics.
As independent, physical science took shape to. 18th century The term "physical" belongs to M.V. Lomonosov, who in 1752 gave the students of St. Petersburg University a course in physics for the first time. He owns the trace. definition: "Physical is a science that explains, on the basis of the provisions and experiments of physics, what happens in mixed bodies during chemical operations." The first scientific journal intended for the publication of articles on physics was founded in 1887 by W. Ostwald and J. van't Hoff.
F physical is the main theoretical. the foundation of modern based on such important branches of physics, as , statistic. physics and, nonlinear dynamics, field theory, etc. It includes the doctrine of the structure of islands, incl. oh and . As separate sections in the physical, they also often single out physical (including), the doctrine of, physical chemistry high-mol. conn. and others. They closely adjoin the physical and are sometimes considered as independent of it. sections , and . Most sections of the physical have fairly clear boundaries for the objects and methods of research, for methodological. features and equipment used.
Modern stage of physical development inherent in-depth analysis general patterns chem. conversions to a pier. level, widespread use of mat. , range extension ext. effects on chem. system (high and cryogenic temperatures, high, strong radiation and magnetic effects), the study of ultrafast processes, methods of energy storage in chemical. in-wah, etc.
The application of quantum theory is primarily in the explanation of chem. phenomena entailed means. increased attention to the level of interpretation and led to the selection of two directions in . A direction based on quantum mechanics. theory and operating on microscopic. level of explanation of phenomena, often called chem. physics, and the direction that operates with ensembles a large number particles, where come into force statistical. laws, physical. With such a subdivision, the boundary between physical chemistry and chem. physics can't. carried out sharply, which is especially evident in the theory of chemical rates. districts.
The doctrine of the structure of the Islands and summarizes an extensive experiment. material obtained by using such physical. methods, such as molecular, studying the interaction. electromagnetic radiation with in-tion in decomp. wavelength ranges, photo-and, and X-ray diffraction methods, methods based on magneto-optical. effects, etc. These methods make it possible to obtain structural data on the electron, on the equilibrium positions and amplitudes of oscillations of nuclei in and condenser. in-ve, about the energy system. levels and transitions between them, about changing the geom. configurations when changing the environment or its individual fragments, etc.
Along with the task of correlating properties in-in with their structure modern. Physical science is also actively involved in the inverse problem of predicting the structure of compounds with given properties.
Very important source information about, their characteristics in decomp. states and characteristics of chem. transformations are the results of quantum chemical. calculations. gives a system of concepts and ideas, which is used in the physical when considering the behavior of chem. compounds per pier. level and when establishing correlations between the characteristics that form the in-in, and St. you of this in-va. Thanks to the results of quantum chemistry. calculations pov-stey potential energy chemical. systems in different and experiment. opportunities recent years, especially development, physical came close to a comprehensive study of St. Comm. in excited and highly excited states, to the analysis of structural features Comm. in such states and the specifics of the manifestation of these features in the dynamics of chemical. transformations.
The limitation of the usual one is that it allows one to describe only equilibrium states and reversible processes. Real irreversible processes are the subject of the problem that arose in the 1930s. 20th century . This area of the physical studies non-equilibrium macroscopic. systems in which the rate of occurrence is locally kept constant (such systems are locally close to equilibrium). It allows us to consider systems with chem. p-tions and mass transfer (), heat, electric. charges, etc.
studies chemical transformations. in-in time, i.e. the speed of chemical. p-tions, the mechanisms of these transformations, as well as the dependence of the chemical. process from the conditions of its implementation. She sets patterns of changeniya of the composition of the transforming system in time, reveals the relationship between the rate of chemical. p-tion and external conditions, and also studies the factors affecting the speed and direction of chemical. districts.
Most chem. p-tions is a complex multi-stage processes, consisting of individual elementary chem. transformation, transport and transfer of energy. Theoretical chem. kinetics includes the study of the mechanisms of elementary p-tions and calculates such processes based on the ideas and apparatus of the classical. mechanics and quantum theory, is engaged in the construction of models of complex chemical. processes, establishes a relationship between the structure of the chemical. compounds and their reactions. ability. Identification of the kinetic patterns for complex p-tions (formal kinetics) is often based on the mat. and allows you to test hypotheses about the mechanisms of complex p-tions, as well as to establish a system of differentials. ur-tions, describing the results of the implementation of the process at decomp. ext. conditions.
For chem. kinetics is characterized by the use of many physical. research methods that make it possible to carry out local excitations of reactants, to study fast (up to femtosecond) transformations, to automate the registration of kinetic. data with their simultaneous processing on a computer, etc. Intensively accumulates kinetic. information through kinetic , incl. for chem. districts in extreme conditions.
A very important section of the physical, closely related to the chemical. kinetics is the doctrine of, i.e., the change in the speed and direction of chemical. p-tion when exposed to in-in (
science explaining chemical phenomena and establishing their laws on the basis of the general principles of physics. The name of the science Physical Chemistry was introduced by M.V. Lomonosov, who for the first time (1752 1753) formulated its subject and tasks and established one ... ... Big Encyclopedic Dictionary
PHYSICAL CHEMISTRY- PHYSICAL CHEMISTRY, “a science that explains, on the basis of provisions and experiments, the physical cause of what happens through chem. operations in complex bodies. This definition was given to her by the first physicochemist M.V. Lomonosov in a course read by ... Big Medical Encyclopedia
PHYSICAL CHEMISTRY, the science that studies the physical changes associated with CHEMICAL REACTIONS, as well as the relationship between physical properties and chemical composition. The main sections of physical chemistry THERMODYNAMICS, dealing with changes in energy in ... ... Scientific and technical encyclopedic dictionary
Physical chemistry- - a branch of chemistry in which they study Chemical properties substances based physical properties their constituent atoms and molecules. Modern physical chemistry is a broad interdisciplinary field bordering on various branches of physics… Encyclopedia of terms, definitions and explanations of building materials
PHYSICAL CHEMISTRY, explains chemical phenomena and establishes their laws on the basis of the general principles of physics. Includes chemical thermodynamics, chemical kinetics, the doctrine of catalysis, etc. The term physical chemistry was introduced by M.V. Lomonosov in 1753 ... Modern Encyclopedia
Physical chemistry- PHYSICAL CHEMISTRY, explains chemical phenomena and establishes their patterns based on the general principles of physics. It includes chemical thermodynamics, chemical kinetics, the doctrine of catalysis, etc. The term “physical chemistry” was introduced by M.V. Lomonosov in ... ... Illustrated Encyclopedic Dictionary
PHYSICAL CHEMISTRY- section of chem. science, studying chemistry. phenomena based on the principles of physics (see (1)) and physical. experimental methods. F. x. (like chemistry) includes the doctrine of the structure of matter, chem. thermodynamics and chemistry. kinetics, electrochemistry and colloidal chemistry, teaching ... ... Great Polytechnic Encyclopedia
Exist., number of synonyms: 1 physical (1) Dictionary of ASIS synonyms. V.N. Trishin. 2013 ... Synonym dictionary
physical chemistry- — EN physical chemistry A science dealing with the effects of physical phenomena on chemical properties. (Source: LEE) … … Technical Translator's Handbook
physical chemistry- - a science that explains chemical phenomena and establishes their patterns based on physical principles. Dictionary of Analytical Chemistry ... Chemical terms
Books
- Physical chemistry , A. V. Artemov , The textbook was created in accordance with the Federal State educational standard in the areas of preparation of bachelors, providing for the study of the discipline `Physical Chemistry`.… Category: Textbooks for universities Series: Higher education Publisher: Drofa, Manufacturer: Bustard,
- Physical chemistry , Yu. Ya. Kharitonov , The textbook outlines the fundamentals of physical chemistry in accordance with exemplary program in the discipline "Physical and colloidal chemistry" for the specialty 060301 "Pharmacy" . The publication is intended… Category: Physical chemistry. Chemical physics Publisher:
Phys. chemistry - the science of the laws of chemical processes and chemical. phenomena.
Subject of physical chemistry explanation of chem. phenomena based on more general laws of physics. Physical chemistry considers two main groups of issues:
1. Study of the structure and properties of a substance and its constituent particles;
2. The study of the processes of interaction of substances.
Physical chemistry aims to study the relationship between m / y chemical and physical phenomena. Knowledge of such relationships is necessary in order to study more deeply the chemical reactions that occur in nature and are used in technology. processes, control the depth and direction of the reaction. The main goal of the discipline Physical Chemistry is the study of general relationships and patterns of chemical. processes based on the fundamental principles of physics. Physical chemistry applies physical. theories and methods for chemical phenomena.
It explains WHY and HOW the transformations of substances occur: chem. reactions and phase transitions. WHY - chemical thermodynamics. AS - chemical kinetics.
Basic concepts of physical chemistry
The main object of chem. thermodynamics is a thermodynamic system. Thermodynamic system - any body or set of bodies capable of exchanging energy and matter with itself and with other bodies. Systems are divided into open, closed and isolated. open and I - thermodynamic system exchanges with external environment and in-tion and energy. Closed and I - a system in which there is no exchange of water with environment, but it can exchange energy with it. isolated and I -system volume remains constant and is deprived of the opportunity to exchange with the environment and energy and in-tion.
The system can be homogeneous (homogeneous) or heterogeneous (heterogeneous ). Phase - this is a part of the system, which in the absence of an external force field has the same composition at all its points and the same thermodynamic. St. you and separated from other parts of the system by the interface. The phase is always homogeneous, i.e. homogeneous, so a single-phase system is called homogeneous. A system consisting of several phases is called heterogeneous.
System properties are divided into two groups: extensive and intensive.
In thermodynamics, the concepts of equilibrium and reversible processes are used. equilibrium is a process that goes through a continuous series of equilibrium states. Reversible thermodynamic process is a process that can be carried out in reverse without leaving any changes in the system and environment.
2. I-th law of thermodynamics. Internal energy, heat, work.
First law of thermodynamics directly related to the law of conservation of energy. Based on this law, it follows that in any isolated system, the energy supply remains constant. Another formulation of the first law of thermodynamics follows from the law of conservation of energy - the impossibility of creating a perpetual motion machine (perpetuum mobile) of the first kind, which would produce work without spending energy on it. The formulation, especially important for chemical thermodynamics,
The first principle is its expression through the concept of internal energy: internal energy is a state function, i.e. its change does not depend on the path of the process, but depends only on the initial and final state of the system. Change in the internal energy of the system U can occur through heat exchange Q and work W with the environment. Then it follows from the law of conservation of energy that the heat Q received by the system from outside is spent on the increment of internal energy ΔU and the work W done by the system, i.e. Q=Δ U+W. Given at alignment is
mathematical expression of the first law of thermodynamics.
Ibeginning of thermodynamics its wording:
in any isolated system, the energy supply remains constant;
different forms of energy pass into each other in strictly equivalent quantities;
perpetual motion machine (perpetuum mobile) of the first kind is impossible;
internal energy is a state function, i.e. its change does not depend on the path of the process, but depends only on the initial and final state of the system.
analytic expression: Q = D U + W ; for an infinitesimal change in quantities d Q = dU + d W .
The 1st law of thermodynamics sets the ratio. m / y heat Q, work A and change int. system energy ΔU. Change int. The energy of the system is equal to the amount of heat communicated to the system minus the amount of work done by the system against external forces.
Equation (I.1) - mathematical notation of the 1st law of thermodynamics, equation (I.2) - for an infinitesimal change in comp. systems.
Int. energy-state function; this means that the change-e ext. energy ΔU does not depend on the transition path of the system from state 1 to state 2 and is equal to the difference between the values of ext. energies U2 and U1 in these states: (I.3)
Int. The energy of a system is the sum of the potential energy of the interaction. all particles of the body m / y and the kinetic energy of their movement (without taking into account the kinetic and potential energies of the system as a whole). Int. the energy of the system depends on the nature of the island, its mass and on the parameters of the state of the system. She's age. with an increase in the mass of the system, since it is an extensive property of the system. Int. energy is denoted by the letter U and is expressed in joules (J). In the general case, for a system with a quantity of 1 mol. Int. energy, like any thermodynamic. St. in the system, yavl-Xia function comp. Directly in the experiment, only changes in the internal energy. That is why in calculations they always operate with its change U2 –U1 = U.
All changes to the internal energies are divided into two groups. The 1st group includes only the 1st form of the transition of motion by chaotic collisions of the molecules of two adjoining bodies, i.e. by conduction (and at the same time by radiation). The measure of the movement transmitted in this way is heat. concept warmth associated with the behavior of a huge number of particles - atoms, molecules, ions. They are in constant chaotic (thermal) motion. Heat is a form of energy transfer. The second way to exchange energy is Job. This exchange of energy is due to the action performed by the system, or the action performed on it. Typically, work is denoted by the symbol W. Work, like heat, is not a function of the state of the system, so the value corresponding to infinitesimal work is denoted by the partial derivative symbol - W.
3rd ed., rev. - M.: graduate School, 2001 - 512 p., 319 p.
The textbook is compiled in accordance with the program in physical chemistry.
The first book details the following sections of the course: quantum mechanical foundations of the theory chemical bond, the structure of atoms and molecules, spectral methods for studying the molecular structure, phenomenological and statistical thermodynamics, thermodynamics of solutions and phase equilibria.
In the second part of the section of the course of physical chemistry, electrochemistry, chemical kinetics and catalysis are presented on the basis of the concepts developed in the first part of the book - the structure of matter and statistical thermodynamics. The `Catalysis` section reflects the kinetics of heterogeneous and diffusion processes, adsorption thermodynamics and questions of reactivity.
For university students enrolled in chemical engineering specialties.
Book 1.
Format: djvu
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Book 2.
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TABLE OF CONTENTS Book 1.
Preface. 3
Introduction 6
Section one. Quantum-mechanical substantiation of the theory of molecular structure and chemical bond
Chapter 1. The structure of the atom 9
§ 1.1. Quantum mechanical features of microparticles 9
§ 1.2. Hydrogen atom 11
§ 1.3. Atomic orbitals of a hydrogen-like atom 14
§ 1.4. Electron spin 21
§ 1.5. Multielectron atoms 23
§ 1.6. Pauli Principle 26
§ 1.7. Electronic configurations of atoms 28
Chapter 2. Molecules. Theoretical methods used in the study of the structure of molecules and chemical bonding 34
§ 2.1. Molecule. potential surface. Equilibrium configuration 34
§ 2.2. Theory of chemical bond and its problems. Schrödinger equation for molecules 39
§ 2.3. Variational Method solutions of the Schrödinger equation 42
§ 2.4. Two main methods of the theory of the structure of molecules. Valence bond method and molecular orbital method 44
§ 2.5. Basic ideas of the molecular orbital method 49
§ 2.6. Approximate description of the molecular orbital in the MO LCAO 50 method
§ 2.7. The II molecule in the MO LCAO method. Calculation of energy and wave function by variational method 53
§ 2.8. Molecule H in the MO LCAO method. Covalent bond 58
Chapter 3. Diatomic molecules in the MO LCAO method 62
§ 3.1. Molecular orbitals of homonuclear diatomic molecules 62
§ 3.2. Electronic configurations and properties of homonuclear molecules formed by atoms of elements of the first and second periods 65
§ 3.3. Heteronuclear diatomic molecules 73
§ 3.4. polar connection. Electric dipole moment of a molecule 78
§ 3.5. Saturability covalent bond 81
§ 3.6. Donor-acceptor bond 82
§ 3.7. Ionic bond. The degree of polarity of the chemical bond 84
Chapter 4. Polyatomic molecules in the MO method 88
§ 4.1. Molecular orbitals in polyatomic molecules. Orbital symmetry. Delocalized and localized orbitals. HgO 88 molecule
§ 4.2. Description of the methane molecule. Delocalized and localized MOs. Hybridization of orbitals 95
§ 4.3. On the prediction of equilibrium configurations of molecules 99
§ 4.4. Nonrigid Molecules 101
§ 4.5. Molecules with multiple bonds in the MO LCAO method 104
§ 4.6. Hückel method 108
§ 4.7. Description of aromatic systems in the MOX 110 method
§ 4.8. Chemical bond in coordination compounds. Ligand field theory 117
§ 4.9. Ionic bonding in a crystal 126
Chapter 5. Intermolecular interaction 129
§ 5.1. Van der Waals forces. Other types of non-specific interactions 129
§ 5.2. Hydrogen bond 136
Section two. Spectral methods for studying the structure and energy states of molecules
Chapter 6. General information about molecular spectra. Elements of the theory of molecular spectra 141
§ 6.1. Intramolecular motion and electromagnetic spectrum. 141
§ 6.2. Molecular spectra emission, absorption and Raman scattering. EPR and NMR spectra 145
§ 6.3. Rotational spectrum of a diatomic molecule (rigid rotator approximation) 150
§ 6.4. Vibrational-rotational spectrum of a diatomic molecule. Harmonic Oscillator Approximation 156
§ 6.5. The molecule is an anharmonic oscillator. Structure of the vibrational spectrum 162
§ 6.6. Electronic spectra. Determination of the dissociation energy of diatomic molecules 169
§ 6.7. Rotational spectra and strict polyatomic molecules.... 171
§ 6.8. Vibrations, spectrum and structure of polyatomic molecules 175
§ 6.9. Use of vibrational spectra to determine the structure of molecules 180
§ 6.10. Influence of the intermolecular interaction of the medium and state of aggregation on the vibrational spectrum 183
Section three. Chemical thermodynamics
Chapter 7 General concepts. The first law of thermodynamics and its application 186
§ 7.1. Subject and tasks of chemical thermodynamics 186
§ 7.2. Basic concepts and definitions of chemical thermodynamics 188
§ 7.3. First law of thermodynamics. Non-circular processes 199
§ 7.4. Heat capacity 202
§ 7.5. Influence of temperature on heat capacity. Temperature series.. 208
§ 7.6. Quantum theory heat capacity of a crystalline substance 211
§ 7.7. Quantum statistical theory of heat capacity gaseous substance 215
§ 7.8. thermal effects. Hess Law 217
§ 7.9. Application of Hess' law to the calculation of thermal effects 220
§ 7.10. Dependence of thermal effect on temperature. Kirchhoff equation 227
Chapter 8. The second law of thermodynamics and its application 235
§ 8.1. Spontaneous and non-spontaneous processes. The Second Law of Thermodynamics 235
§ 8.2. Entropy 236
§ 8.3. Entropy change in non-static processes 239
§ 8.4. Entropy change as a criterion of directionality and equilibrium in an isolated "system 240
§ 8.5. Characteristic functions. Thermodynamic potentials 241
§ 8.6. Criteria for the possibility of a spontaneous process and equilibrium in closed systems 249
§ 8.7. Entropy change in some processes 251
§ 8.8. Gibbs energy of a mixture of ideal gases. Chemical potential 261
§ 8.9. General conditions of chemical equilibrium 265
§ 8.10. The law of active masses. Equilibrium constant for gas phase reactions 266
§ 8.11. Reaction isotherm equation 271
§ 8.12. Using the law of mass action to calculate the composition of an equilibrium mixture 273
§ 8.13. Effect of temperature on chemical equilibrium. Reaction isobar equation 282
§ 8.14. Integral form of dependence of Gibbs energy and equilibrium constant on temperature 284
§ 8.15. Chemical equilibrium in heterogeneous systems 286
Chapter 9. The Third Law of Thermodynamics and the Calculation of Chemical Equilibrium 289
§ 9.1. Thermal Nernst theorem. Third law of thermodynamics 289
§ 9.2. Calculation of the change in standard Gibbs energy and equilibrium constant by the method of Temkin - Schwartzman 294
§ 9.3. Calculation of the change in the standard Gibbs energy and the equilibrium constant using the functions of the reduced Gibbs energy 297
§ 9.4. Adiabatic reactions 299
Chapter 10. Chemical equilibrium in real systems 303
§ 10.1. Fugacity and coefficient of fugacity of gases 303
§ 10.2. Calculation of chemical equilibrium in a real gas system at high pressures 312
§ 10.3. Calculation of chemical equilibrium in systems in which several reactions occur simultaneously 314
Chapter 11. Introduction to statistical thermodynamics 320
§ 11.1. Statistical physics and statistical thermodynamics. Macroscopic and microscopic description of the state of the system 320
§ 11.2. Microscopic description of the state by the method of classical mechanics 323
§ 11.3. Microscopic description of the state by the method of quantum mechanics. Quantum statistics 324
§ 11.4. Two types of averages (microcanonical and canonical averages) 325
§ 11.5. Relationship between entropy and statistical weight. Statistical nature of the second law of thermodynamics 326
§ 11.6. Thermostat system. Canonical Gibbs distribution. 330
§ 11.7. The sum over the states of the system and its connection with energy. Helmholtz 335
§ 11.8. Sum over particle states 337
§ 11.9. Expression of thermodynamic functions in terms of the sum over the states of the system 340
§ 11.10. The sum over the states of a system of one-dimensional harmonic oscillators. Thermodynamic properties of a monatomic solid body according to Einstein's theory 343
§ 11.11. Boltzmann quantum statistics. Maxwell's law of molecular velocity distribution 346
§ 11.12. Fermi - Dirac and Bose - Einstein statistics 352
§ 11.13. General formulas for calculating thermodynamic functions from molecular data 353
§ 11.14 Calculation of the thermodynamic functions of an ideal gas under the assumption of rigid rotation and harmonic vibrations of molecules 357
Section four. Solutions
Chapter 12 general characteristics solutions 365
§ 12.1. Classification of mortars 365
§ 12.2. Concentration of solutions 367
5 12.3. Specificity of solutions. The role of intermolecular and chemical interactions, the concept of solvation 368
§ 12.4. The main directions in the development of the theory of solutions 372
§ 12.5. Thermodynamic conditions for the formation of solutions 374
§ 12.6. Partial molar values 375
§ 12.7. Basic Methods for Determining Partial Molar Values 379
§ 12.8. Partial and relative partial molar enthalpies 381
§ 12.9. Heats of dissolution and dilution 382
§ 12.10. Thermodynamic properties of ideal liquid solutions 386
§ 12.11.3 Raoult law 390
§ 12.12. Boiling point of an ideal solution 392
§ 12.13. Freezing point of an ideal solution 395
§ 12.14.0 smotic pressure of an ideal solution 397
§ 12.15 Non-ideal solutions 400
§ 12.16. Extremely dilute, regular and athermal solutions 402
§ 12.17. Activity. Activity coefficient. Standard state 404
§ 12.18.0smotic coefficient 407
§ 12.19. Methods for determining activities 409
§ 12.20. Relationship of the activity and activity coefficient with the thermodynamic properties of the solution and excess thermodynamic functions 412
Section Five. Phase Equilibria
Chapter 13. Thermodynamic theory of phase equilibria 415
§ 13.1. Basic concepts 415
§ 13.2. Phase equilibrium conditions 418
§ 13.3. Gibbs phase rule 419
Chapter 14 Single Component Systems 421
§ 14.1. Application of the Gibbs phase rule to one-component systems 421
§ 14.2. Phase transitions of the first and second kind 422
§ 14.3. Equation of Clapeyron - Clausius 425
§ 14.4. Saturated steam pressure 423
§ 14.5. State diagrams of one-component systems 429
§ 14.6. Carbon dioxide state diagram 431
§ 14.7. Water Status Diagram 432
§ 14.8. Sulfur state diagram 433
§ 14.9. Enantiotropic and monotropic phase transitions 435
Chapter 15. Two-component systems 436
§ 15.1. Physical and chemical analysis method 436
§ 15.2. Application of the Gibbs phase rule to two-component systems 437
§ 15.3. Equilibrium gas - liquid solution in two-component systems 438
§ 15.4. Equilibrium liquid - liquid in two-component systems 442
§ 15.5. Equilibrium vapor - liquid solution in two-component systems 444
§ 15.6. Physical and chemical bases of solution distillation 453
§ 15.7. Equilibrium crystals - liquid solution in two-component systems 457
§ 15.8. Equilibrium liquid - gas and crystals - gas (steam) in two-component systems 476
§ 15-9. State Diagram Calculations 476
Chapter 16. Three-component systems 482
§ 16.1. Application of the Gibbs phase rule to three-component systems 482
§ 16.2. Graphical representation of the composition of a three-component system 482
§ 16.3. Equilibrium crystals - liquid solution in three-component systems 484
§ 16.4. Equilibrium liquid - liquid in three-component systems 489
§ 16.5. Distribution of a solute between two liquid phases. Extraction 491
Appendix 495
Index 497
TABLE OF CONTENTS Book 2.
Preface 3
Section six. Electrochemistry
Chapter 17. Solutions, electrolytes 4
§ 17.1. Electrochemistry subject 4
§ 17.2. Specificity of electrolyte solutions 5
§ 17.3. Electrolytic dissociation in solution 6
§ 17.4. Average ionic activity and activity factor 10
§ 17.5. Basic concepts of the electrostatic theory of strong electrolytes Debye and Hückel 13
§ 17.6. Basic concepts of ion association theory 22
§ 17.7. Thermodynamic properties of ions 24
§ 17.8. Thermodynamics of ionic solvation 28
Chapter 18. Non-equilibrium phenomena in electrolytes. Electrical conductivity of electrolytes 30
§ 18.1. Basic concepts. Faraday's laws 30
§ 18.2. Movement of ions in an electric field. Ion transport numbers. 32
§ 18.3. Electrical conductivity of electrolytes. Electrical conductivity 37
§ 18.4. Electrical conductivity of electrolytes. Molar electrical conductivity 39
§ 18.5. Molar electrical conductivity of hydronium and hydroxide ions 43
§ 18.6. Electrical conductivity of non-aqueous solutions 44
§ 18.7. Electrical conductivity of solid and molten electrolytes 46
§ 18.8. Conductometry 47
Chapter 19. Equilibrium electrode processes 49
§ 19.1. Basic concepts 49
§ 19.2. EMF of an electrochemical system. Electrode potential 51
§ 19.3. Occurrence of a potential jump at the solution-metal interface 53
§ 19.4. Diffusion potential 55
§ 19.5. The structure of the electrical double layer at the solution-metal interface 56
§ 19.6. Thermodynamics of reversible electrochemical systems 60
§ 19.7. Classification of reversible electrodes 64
§ 19.8. Electrode potentials in non-aqueous solutions 74
§ 19.9. Electrochemical circuits 75
§ 19.10. Application of the theory of electrochemical systems to the study of equilibrium in solutions 82
§ 19.11. Potentiometry 85
Section seven. Kinetics of chemical reactions
Chapter 20. Laws of chemical kinetics 93
§ 20.1. General concepts and definitions 93
§ 20.2. Speed chemical reaction 95
§ 20.3. The law of mass action and the principle of independence of reactions 101
Chapter 21. Kinetics of chemical reactions in closed systems. 105
§ 21.1. Unilateral first order reactions 105
§ 21.2. Unilateral Second Order Reactions 109
§ 21.3. One-way reactions of the nth order 111
§ 21.4. Methods for determining the order of the reaction 112
§ 21.5. Bilateral reactions of the first order 113
§ 21.6. Bilateral reactions of the second order 116
§ 21.T. Parallel one-way reactions 117
§ 21.8. Unilateral sequential reactions 119
§ 21.9. Method of quasi-stationary concentrations 125
Chapter 22. Kinetics of reactions in open systems 127
§ 22.1. Reaction kinetics in a perfectly mixed reactor 127
§ 22.2. Reaction kinetics in a plug flow reactor 129
Chapter 23. The Theory of the Elementary Act chemical interaction 133
§ 23.1. Elementary chemical act 133
§ 23.2. Theory of active collisions 137
§ 23.3. Theory of the activated complex 141
§ 23.4. Preexponential factor in the Arrhenius equation according to the transition state theory 154
§ 23.5. MO symmetry and activation energy of chemical reactions 159
Chapter 24. Kinetics of reactions in solutions, chain and photochemical reactions 166
§ 24.1. Features of the kinetics of reactions in solutions 166
§ 24.2. Influence of medium on the reaction rate constant 170
§ 24.3. Kinetics of ionic reactions in solutions 178
§ 24.4. Chain reactions 181
§ 24.5. Photochemical reactions 189
Chapter 25. Kinetics of electrode processes 196
§ 25.1. The rate of an electrochemical reaction. exchange current 196
§ 25.2. Electrode polarization 197
§ 25.3. Diffusion overvoltage 199
§ 25.4. Electrochemical overvoltage 205
§ 25.5. Other types of overvoltage 210
5 25.6. Temperature-kinetic method for determining the nature of polarization in electrochemical processes 211
§ 25.7. Overvoltage during electrolytic hydrogen evolution 213
§ 25.8. Electrolysis. Decomposition voltage 217
§ 25.9. Polarization phenomena in chemical sources electric current 220
§ 25.10. Electrochemical corrosion of metals. passivity of metals. Corrosion protection methods 222
Section eight. Catalysis
Chapter 26. Principles of catalytic action 228
§ 26.1. Basic concepts and definitions 228
§ 26.2. Features of the kinetics of catalytic reactions 232
§ 26.3. Activation energy of catalytic reactions 237
§ 26.4. Interaction of reagents with a catalyst and principles of catalytic action 241
Chapter 27. Homogeneous catalysis 245
§ 27.1. Acid-base catalysis 246
§ 27.2. Redox catalysis 255
§ 27.3. Enzymatic catalysis 260
§ 27.4. Autocatalysis, inhibition and periodic catalytic reactions 266
§ 27.5. Application in industry and prospects for the development of homogeneous catalysis 271
Chapter 28. Heterogeneous catalysis. 273
§ 28.1. Surface structure of heterogeneous catalysts 273
§ 28.2. Adsorption as a stage of heterogeneous catalytic reactions 277
§ 28.3. Mechanism of heterogeneous catalytic reactions 282
§ 28.4. Kinetics of heterogeneous catalytic reactions on an equally accessible surface 285
§ 28.5. Macrokinetics of heterogeneous catalytic processes 292
§ 28.6. Application of heterogeneous catalysis in industry 300
Literature 303
Application 305
Index 312
Contents 316
Ministry of Education Russian Federation Tomsk Polytechnic University __________________________________________________________________________ N. A. Kolpakova, V. A. Kolpakov, S. V. Romanenko PHYSICAL CHEMISTRY Textbook Part I Tomsk 2004 UDC 541.1 Physical chemistry. Textbook / N.A. Kolpakova, V.A. Kolpakov, S.V. Romanenko. - Tomsk: Ed. TPU, 2004. - Part 1. - 168 p. IN study guide the following sections of "Physical Chemistry" are considered: the basic laws of thermodynamics, chemical and phase equilibrium, thermodynamics of nonelectrolyte solutions. The manual was prepared at the Department of Physical and Analytical Chemistry of TPU and is intended for students of correspondence courses in chemical specialties. Published by order of the Editorial and Publishing Council of Tomsk Polytechnic University Reviewers: Kurina L.N. – Prof. Department of Physical Chemistry, TSU, Doctor of Chem. sciences; Buinovsky A.S. - Head. cafe Chemistry TPU STU, doctor of chem. Sciences. © Tomsk Polytechnic University, 2004 © Authors, 2004 CHAPTER 1 . INTRODUCTION TO PHYSICAL CHEMISTRY 1.1. BRIEF HISTORICAL OUTLINE OF THE DEVELOPMENT OF PHYSICAL CHEMISTRY The name and definition of the content of physical chemistry was first given by M. V. Lomonosov (1752): “Physical chemistry is a science that must, on the basis of the provisions and experiments of physical scientists, explain the reason for what happens through chemical operations in complex bodies” . The teaching of physical chemistry in Russia as an independent science was introduced by prof. N. N. Beketov in 1860 at Kharkov University. The most important theoretical and experimental studies Lomonosov led him to discoveries that have not lost their significance even now. Lomonosov came close to the correct definition of the principle of conservation of matter and motion, the kinetic nature of heat, and also noted the impossibility of a spontaneous transfer of heat from a colder body to a warmer one, which is currently one of the formulations of the second law of thermodynamics. Over the next century, research was carried out, on the basis of which many important discoveries and generalizations were made. K. V. Scheele in Sweden (1773) and Fontana in France (1777) discovered the adsorption of gases; T. E. Lovits in Russia (1785) discovered adsorption from solutions. A. L. Lavoisier and P. S. Laplace in France (1779–1784) studied the heat capacities of substances and the heat effects of reactions. IN early XIX V. G. Davy in England and L. J. Tenard in France discovered catalytic reactions, and J. J. Berzelius in Sweden (1835) further developed the idea of catalysis. The foundations of electrochemistry were laid by research on galvanic cells, electrolysis, and current transfer in electrolytes. Galvani and A. Volta in Italy created in 1799 a galvanic cell. VV Petrov in Russia (1802) discovered the phenomenon of an electric arc. T. Grotgus in Russia in 1805 laid the foundations for the theory of electrolysis. In 1800, G. Davy put forward the electro chemical theory interactions of substances: he widely used electrolysis for chemical research. M. Faraday, a student of Davy, in 1833-1834 formulated the quantitative laws of electrolysis. B. S. Jacobi in Russia, solving the problems of the practical use of the electrolysis process, discovered in 1836 galvanoplasty. In the first half of the XIX century. thanks to the works of D. Dalton in England (1801–1803), J. L. Gay-Lussac in France (1802) and A. Avogadro in Italy (1811), who discovered the most important laws of the gaseous state, atomistic ideas were widely developed. The works of G. I. Hess (1802–1856) on thermochemistry belong to the same period. K. Guldberg and P. Waage in Norway (1864–1867), J. W. Gibbs in the USA (1873–1878) developed the thermodynamic theory of chemical equilibrium, and A. L. Le Chatelier in France (1884) discovered general principle equilibrium shifts when external conditions change. In the works of the Dutch chemist J. H. van't Hoff, the thermodynamic theory of chemical equilibrium was developed. He also developed the quantitative theory of dilute solutions (1885–1889). The transfer of electricity in solutions was studied in Germany by I. V. Gittorf and F. V. G. Kohlrausch. The Swedish scientist S. A. Arrhenius developed in 1883–1887. theory electrolytic dissociation. A. M. Butlerov, who created the theory of the structure of organic compounds, left a deep mark on the development of physical chemistry. The great Russian chemist D. I. Mendeleev (1834–1907) discovered the existence of a critical temperature (1860), deduced general equation states of gases, (1874) and developed the chemical theory of solutions (1887). D. P. Konovalov (1889), a student of Mendeleev, is one of the founders of the theory of solutions. At the end of the XIX century. a number of major discoveries were made in the field of the doctrine of the structure of matter, which proved the complexity of the structure of the atom and played a huge role in the development of physical chemistry. These include the discoveries of the electron by J. B. Perrin (1895) and J. Thomson (1897), the quantum nature of light by R. Planck (1900), the existence of light pressure by P. N. Lebedev (1899), the study (since 1898 of ) phenomena of radioactivity by P. Curie and M. Sklodowska-Curie. By the beginning of the XX century. physical chemistry was defined as the science that studies the structure of matter, chemical thermodynamics, including thermochemistry and the theory of equilibrium, solutions, chemical kinetics and electrochemistry. New theoretical methods and studies of the structure of atoms, molecules, and crystals came to the fore. The doctrine of the structure of matter, especially the structure of atoms and molecules, developed most rapidly in the 20th century. A major achievement in this area was the nuclear theory of the atom, proposed by E. Rutherford (1911) and developed in the first quantitative theory of the hydrogen atom, developed by the Danish physicist N. Bohr (1913). The study of the nature of the chemical bond and the structure of molecules developed in parallel with the study of the structure of the atom. By the early 1920s, W. Kossel and G. N. Lewis had developed the fundamentals of the electronic theory of chemical bonding. VG Geitler and F. London (1927) developed the quantum-mechanical theory of chemical bonding. Based on the largest discoveries of physics in the field of atomic structure and using the theoretical methods of quantum mechanics and statistical physics, as well as new experimental methods, such as X-ray analysis, spectroscopy, mass spectroscopy, magnetic methods, the method of labeled atoms and others, physicists and physical chemists have made great strides in studying the structure of molecules and crystals and in understanding the nature of the chemical bond. The theory of the rates of chemical reactions, i.e., chemical kinetics, has been greatly developed, and is now associated specifically with studies of the structure of molecules and the strength of bonds between atoms in a molecule. New branches of physical chemistry have arisen and are successfully developing: magnetochemistry, radiation chemistry, physical chemistry of high polymers, physical chemistry of silicates, gas electrochemistry, etc. Like other sciences, physical chemistry and its individual branches arose or began to develop especially successfully in periods when one or another practical need necessitated the rapid development of some branch of industry, and this development required a strong theoretical basis. Here it is necessary to note the major studies of N. S. Kurnakov on physicochemical analysis, the work in the field of electrochemistry by A. N. Frumkin, the creation of the theory of chain reactions by N. N. Semenov, and the development of the theory of heterogeneous catalysis by A. A. Balandin. Physical chemistry plays a leading role in solving numerous problems facing chemical science and practice. At present, physical chemistry is an independent discipline with its own research methods and is theoretical basis applied chemical and technological disciplines. 1.2. SUBJECT AND OBJECTIVES OF PHYSICAL CHEMISTRY Physical chemistry is the science of regularities of chemical processes and physical phenomena. The main task Physical chemistry is the study and explanation of the main regularities that determine the direction of chemical processes, their speed, the influence of the environment, impurities, radiation, the conditions for obtaining the maximum yield of a useful product. The study of physical chemistry makes it possible to understand the laws of chemistry, as well as to predict and control chemical phenomena. Modern physical chemistry makes it possible to solve the problems of efficient production control, intensification and automation of production processes. It serves as the theoretical foundation of chemical technology. Such important production processes in chemical technology as the synthesis and oxidation of ammonia, the contact production of sulfuric acid, the production of ethanol from natural gas, oil cracking and many others are based on the results of physical and chemical studies of the reactions underlying these 5 processes. Without physical chemistry, it is impossible to solve the problem of creating substances with desired properties, develop new current sources, and many other issues of efficient production. Therefore, knowledge of physical chemistry for future process engineers opens up great opportunities for solving various problems encountered in the practical activities of an engineer at factories and research institutes. The name of the science - "physical chemistry" - reflects both the history of its emergence at the junction of two sciences - physics and chemistry, as well as the fact that it widely uses the theoretical laws and experimental methods of physics in the study of chemical phenomena. 1.3. CLASSIFICATION OF METHODS OF PHYSICAL CHEMISTRY Several theoretical methods are used in physical chemistry. Quantum-chemical method to describe chemical transformations uses the properties elementary particles. Using the laws of quantum mechanics, the properties and reactivity of molecules are described, as well as the nature of the chemical bond based on the properties of the elementary particles that make up the molecules. The thermodynamic (phenomenological) method is based on several laws (postulates), which are a generalization of experimental data. It makes it possible, on their basis, to find out the energy properties of the system, to predict the course of the chemical process and its result by the moment of equilibrium. The quantum-statistical method explains the properties of substances on the basis of the properties of the molecules that make up these substances. The kinetic method allows you to establish the mechanism and create a theory of chemical processes by studying the change in the rate of chemical reactions from various factors. Physical chemistry is characterized by the widespread use of mathematics, which not only makes it possible to most accurately express theoretical laws, but is also a necessary tool for establishing them. 6 CHAPTER 2 . BASIC LAWS OF THERMODYNAMICS The word "thermodynamics" comes from the Greek therme - heat and dynamis - force. Thermodynamics - the science of transformations various kinds energy from one to the other. Chemical thermodynamics studies the transformation of various types of energy occurring during the course of chemical reactions. 2.1. BASIC CONCEPTS OF CHEMICAL THERMODYNAMICS A system is a separate body or a group of bodies interacting and separated from the environment by a real or imaginary shell (boundary). An open system is a system that exchanges substances (mass) and energy (for example, heat) with the external environment. An isolated system (or closed system) is a system that does not exchange heat and work with the environment. The energy and volume of an isolated system are constant in time. An example of such a system is, for example, a thermos. If the boundary does not pass heat, then the process occurring in the system is called adiabatic. When a system exchanges heat and work with the environment, changes occur both in the system and in the environment. Thermodynamic systems can be homogeneous or heterogeneous. If there are no interfaces inside the system separating parts of the system with different composition or structure, then this system is called homogeneous. Accordingly, a heterogeneous system is a system consisting of various parts that differ in structure or chemical composition. These parts are called phases. Thus, a phase is a part of a heterogeneous system limited by the interface and characterized by the same physical and chemical properties at all points. Each system consists of one or more substances. Individual chemical substances, which can be isolated from the system and exist independently outside it as a separate phase, are called the constituent substances of the system. For example, in a glass there is water in which a platinum plate is lowered. Above the glass is a mixture of gases: oxygen, hydrogen and nitrogen. This system is three-phase, it contains five constituent substances. 7 The thermodynamic state of a system is a set of values of independent variables (system parameters) that determine its properties. Any property of a system can be called a thermodynamic state parameter if it is considered as one of the independent variables that determine the state of the system. Thermodynamics considers matter as a continuous medium and uses for research such thermodynamic parameters that are the result of the action of a large number of particles (macroparameters). For example, the macroparameters of a chemical reaction that proceeds even under “normal conditions” are temperature, pressure, volume, concentration, strength of gravitational, magnetic, electric and electromagnetic fields, etc. “Normal conditions” is a temperature of 20– 25 °C, atmospheric pressure, i.e. about 101 kPa, acceleration due to gravity - on average about 9.8 m/s2, tension magnetic field- an average of about 40 A/m, electric field strength - an average of about 130 V/m, visible light illumination - an average of about 500 lux. To characterize the thermodynamic state of a system, it is necessary to know not all properties, but only the smallest number of them, the so-called independent parameters of the system. As a rule, when describing a chemical process occurring on the Earth, we do not indicate the characteristics of the field, since they are constant and therefore do not affect the composition and yield of the reaction products. If the chemical process is carried out in conditions of strong magnetic or electric fields, or under intense ultraviolet irradiation, x-rays or even visible light, then the field parameters will have a significant effect on the composition and yield of the reaction products. In this case, the field parameters must be specified. Thermodynamic parameters are divided into extensive and intensive. Quantities proportional to the mass (or amount of substance) of the considered working fluid or thermodynamic system are called extensive, they are volume, internal energy, enthalpy, etc. Intensive quantities do not depend on the mass of the thermodynamic system. These are, for example, temperature and pressure. Pressure is a physical quantity equal to the ratio of a force uniformly distributed over the surface of a body to the surface area located perpendicular to the force: p \u003d S The unit of pressure in SI - pascal (Pa) is the pressure caused by a force of 1 N, uniformly distributed on a surface of 1 m2 located perpendicular to the direction of force: 1 N/m2 = 1 Pa. In practice, multiple and sub-multiple units of pressure are used: kilopascal 8 (103 Pa = 1 kPa); megapascal (106 Pa = 1 MPa); hectapascal (102 Pa = 1 hPa), as well as an off-system unit - bar (1 bar = 105 Pa). According to the conclusions of the molecular-kinetic theory, the pressure of a gas is the result of impacts of randomly continuously moving molecules against the vessel wall. The simplest relationships between the parameters and the behavior of molecules were obtained for an ideal gas. An ideal gas is understood as a gas consisting of elastic molecules, between which there are no interaction forces, which have a negligibly small intrinsic volume compared to the volume occupied by the gas. Any real gas at a relatively low pressure (close to atmospheric) behaves practically like an ideal one (strictly at p → 0). The equation of state of an ideal gas - the Mendeleev - Clapeyron equation has the form: pV = nRT, where p is the gas pressure, Pa; V - volume, m3; n is the amount of gas, mol; R is the universal gas constant equal to 8.314 J/(mol K); T is the absolute temperature, K. The temperature characterizes the thermal state of the system. Experimentally, the concepts of a warmer and colder body can be established, but the temperature cannot be measured directly. It is determined from the numerical values of other physical parameters that depend on temperature, which is the basis for constructing empirical temperature scales. Such parameters (thermometric parameters) can be various physical quantities. Among them are the volume of a body at constant pressure, pressure at a constant volume, electrical conductivity, thermoelectromotive force, geometric parameters of bodies, brightness of the glow, etc. A device for measuring temperature is called a thermometer. To build any empirical temperature scale, three assumptions are used: 1) the size of a degree is set by choosing the numerical value of ∆T between two reference temperature points - temperature standards; 2) the position of the temperature zero in empirical scales is arbitrary; 3) it is assumed that the thermometric function is linear in a given temperature range. The phase transitions of pure substances are used as reference points. For example, for the empirical Celsius scale, the melting and boiling points of water at atmospheric pressure (0 and 100 degrees, respectively) are taken as reference points. The interval between these temperatures is divided by one hundred equal parts(degrees Celsius - °C). Although an objective temperature scale can be constructed using any theoretically defined thermometric function, thermodynamics uses the ideal gas equation of state as such a function. The gas thermometer makes it possible to carry out the most accurate (close to the absolute temperature scale - the Kelvin scale) temperature measurements. However, determining the temperature on the scale of a gas thermometer is a rather difficult job, which is carried out only to establish the absolute temperatures of a few reference points of phase transitions taken as reference ones. Intermediate temperatures are usually determined by empirical thermometric methods. The International Practical Temperature Scale (IPTS), adopted in 1954, is the most accurate present stage approximation to the absolute temperature scale. In contrast to empirical scales, the MPSH uses one experimental reference temperature point. The temperature of the triple point of water (when ice, water and water vapor are in equilibrium at the same time) was used as such a point. The temperature of the triple point of water is taken in the IPTS as 273.16 K (exactly). At atmospheric pressure, ice melts 0.01° lower. The reference point on the Celsius scale - 0 °C - corresponds to 273.15 K. The numerical value of temperatures for all other reference points (except for the triple point of water) is continuously refined as the accuracy of working with a gas thermometer increases. In 1968, twelve reference points were recommended as reference temperature points, covering the interval from the hydrogen triple point to the melting point of gold. Currently, Celsius temperature (t) is expressed as a relationship with absolute temperature (T), which is: T = 273.15 + t. The properties of a system that can be unambiguously expressed as functions of temperature, pressure, and concentration of the substances that make up the system are called thermodynamic functions. For example, heat capacity, internal energy, entropy, etc. If the change in the thermodynamic function depends only on the initial and final states of the system and does not depend on the path of the process, then such a function is called the state function of the system. A thermodynamic process is any change in a system associated with a change in at least one of the thermodynamic parameters. A circular process or cycle is a process in which a thermodynamic system, having left some initial state and undergoing a series of changes, returns to the same state; in this process, the change in any state parameter is equal to zero. 10
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