Page 20 - Physical Chemistry

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CHAPTER
1

Thermodynamics

CHAPTER OUTLINE

1.1 Physical Chemistry

1.2 Thermodynamics
1.1 PHYSICAL CHEMISTRY
1.3 Temperature
Physical chemistry is the study of the underlying physical principles that govern the
properties and behavior of chemical systems. 1.4 The Mole
A chemical system can be studied from either a microscopic or a macroscopic
viewpoint. The microscopic viewpoint is based on the concept of molecules. The 1.5 Ideal Gases
macroscopic viewpoint studies large-scale properties of matter without explicit use of
1.6 Differential Calculus
the molecule concept. The first half of this book uses mainly a macroscopic viewpoint;
the second half uses mainly a microscopic viewpoint.
1.7 Equations of State
We can divide physical chemistry into four areas: thermodynamics, quantum
chemistry, statistical mechanics, and kinetics (Fig. 1.1). Thermodynamics is a macro- 1.8 Integral Calculus
scopic science that studies the interrelationships of the various equilibrium properties
of a system and the changes in equilibrium properties in processes. Thermodynamics 1.9 Study Suggestions
is treated in Chapters 1 to 13.
1.10 Summary
Molecules and the electrons and nuclei that compose them do not obey classical
mechanics. Instead, their motions are governed by the laws of quantum mechanics
(Chapter 17). Application of quantum mechanics to atomic structure, molecular bond-
ing, and spectroscopy gives us quantum chemistry (Chapters 18 to 20).
The macroscopic science of thermodynamics is a consequence of what is hap-
pening at a molecular (microscopic) level. The molecular and macroscopic levels are
related to each other by the branch of science called statistical mechanics. Statistical
mechanics gives insight into why the laws of thermodynamics hold and allows calcu-
lation of macroscopic thermodynamic properties from molecular properties. We shall
study statistical mechanics in Chapters 14, 15, 21, 22, and 23.
Kinetics is the study of rate processes such as chemical reactions, diffusion, and
the flow of charge in an electrochemical cell. The theory of rate processes is not as
well developed as the theories of thermodynamics, quantum mechanics, and statistical
mechanics. Kinetics uses relevant portions of thermodynamics, quantum chemistry,
and statistical mechanics. Chapters 15, 16, and 22 deal with kinetics.
The principles of physical chemistry provide a framework for all branches of
chemistry.

Figure 1.1
Statistical Quantum
Thermodynamics
mechanics chemistry The four branches of physical
chemistry. Statistical mechanics is
the bridge from the microscopic
approach of quantum chemistry to
the macroscopic approach of
thermodynamics. Kinetics uses
Kinetics portions of the other three
branches.