I.1 - Basic thermochemical relationships

Abstract

Publisher Summary This chapter discusses the basic thermochemical relationships. Since the publication of Gibbs' last paper in the series, “On the equilibrium of heterogeneous substances,” in 1878, all the terms necessary to describe chemical equilibrium have been defined. The chemical potential had been introduced and the relation governing the different types of phase diagram and the Gibbs–Duhem equation had been derived. Electrochemistry can only be treated if the electrical work term is explicitly included. The entire database derived under the conditions is a Gibbs energy, rather than a Helmholtz, enthalpy, or internal energy database. Problems with constant temperature and volume have to be treated in an indirect way, which is no problem for the computer. Using the Maxwell relations, one can easily derive a diagrammatic scheme to relate the Gibbs energy in its natural variables with the other state functions and their natural variables, such as the Helmholtz energy, the enthalpy, and the internal energy.