TABLE OF CONTENTS Thermodynamics addresses those relations among the macroscopic properties of macroscopic systems that do not depend on the properties of its atomic constituents. It is a fact of experience that systems exist whose properties do not change with time, within the limits of measurement. It is also a fact that systems exist whose properties do change with time. In making such statements, the time scale must be considered. Thus, a piece of iron may have properties whose values are constant over some time period, say, one week, but over a period of months or years the iron might develop rust on its surface.
To develop thermodynamic theory, we first restrict our analysis to systems in the absence of external fields, such as gravity or magnetism, and that consist of isotropic phases. An isotropic phase is a homogeneous substance none of whose properties depend on spatial directions. If the system consists of just one phase, then we will call it a simple system. A heterogeneous system is one that consists of several simple systems. The extension of the theory to heterogeneous complex systems, and to systems in external fields, is straightforward once the thermodynamics of simple systems is understood.
A system is said to be in internal equilibrium if none of its properties change with time. Such properties might be the pressure exerted by the system, or its volume, chemical composition, magnetic moment, refractive index, or temperature. Experiments have shown that...
