A rigorous treatment of the phase rule

none2noAfter a critical analysis of the literature, the traditional formulation of the phase rule proposed by Gibbs is stated in a different form and is proved rigorously, together with Gibbs' conjecture on the maximum number of coexisting phases. A new statement of Gibbs' phase rule is proved for closed systems. Then, Hatsopoulos-Keenan's formulation of the phase rule is restated and proved, both for open and for closed systems. The whole treatment of the phase rule presented in this paper holds both in the presence and in the absence of chemical reactions. © 1995 Società Italiana di Fisica.noneZanchini E.; Barletta A.Zanchini E.; Barletta A