ABSTRACT
This chapter introduces a number of new quantities, in particular the so-called thermodynamic potentials, which are needed to provide important links between theoretical and experimental work. The four functions, internal energy (U), enthalpy (H), Helmholtz function (F) and the Gibbs function (G), have a wide applicability throughout thermodynamics, and as a set they are referred to as the four thermodynamic potentials. The chapter presents their properties in turn. In the course of this discussion, the chapter also presents four extremely useful general thermodynamic relations among the four variables, pressure (P), volume (V), temperature (T), and entropy (S), the four Maxwell relations. The chapter shows that, in a process in which the initial and final temperatures are equal to the temperature of the surroundings and where the heat transferred is between the system and the surroundings only, the maximum work that can be obtained from a system is equal to the decrease in F.
