ABSTRACT
In Section 3.13 of Chapter 3, we introduced three thermodynamic potentials that involve combinations of the ˆve variables E, S, P, V, and T. In these special functions, T and S occur together, as do P and V. e conjugate pairs PV and TS, which are products of intensive and extensive variables, have dimensions energy. e thermodynamic potentials are deˆned as follows for a single component system such as a pure gas:
Enthalpy, H = E + PV; (7.1) Helmholtz potential, F = E − TS; (7.2) Gibbs potential, G = E − TS + PV. (7.3)
ese forms for the thermodynamic potentials were obtained in the energy representation with use of Legendre transforms as described in Appendix D and Section 3.13. e potentials are discussed in detail below, and their usefulness in the development of the subject will become apparent in this chapter. e Helmholtz and the Gibbs potentials are particularly important and are involved in bridge relationships between macroscopic and microscopic descriptions of systems.
