A brief discussion of the Gibbs-Duhem equation is given in Sec. 2.4 and some applications are given in Chap. 6. In this appendix we give a derivation of the fundamental equation and we present special forms of the equation as applied to activity coefficients.
Let M be an extensive property of a mixture. For a homogeneous phase, M is a function of temperature, pressure, and mole numbers. The total differential of M is given by
The extensive property M is related to the partial molar properties ...