The Postulates and Laws of Thermodynamics

The points of view about the behavior of macroscopic systems arising from thermodynamics and statistical mechanics are compared and contrasted. The concept of a state function is explained, and the postulates of thermodynamics, which describe fundamental properties of the entropy, are presented. Some are essential postulates, which are always valid, while others, called optional postulates, are very useful when they do apply. The Laws of Thermodynamics are derived from these postulates. With this chapter we begin the formal study of thermodynamics, which represents a detour from the development of the foundations of classical statistical mechanics that we began in Part I.