On equilibrium thermodynamics of open systems and the phase rule (A reply to D. S. Korzhinskii)

Abstract

The recent comments of Korzhinskii (1966) concerning our discussion (1964) of his expanded formal treatment of thermodynamic equilibrium in open geological systems are analyzed. It is shown that these comments in themselves serve to further substantiate the salient points of our 1964 discussion which may be summed up in the following statements. (1) The classical thermodynamic treatment of reversible processes is a perfectly adequate formalism for dealing with states of chemical equilibrium. Since only equilibrium states of open systems are considered by Korzhinskii, it is literally impossible for his treatment to expand upon classical thermodynamics. His treatment, in fact, represents only a severely limited version of that due to Gibbs. (2) This leaves only one possible legitimate reason for introducing the formalities of the Korzhinskii treatment ( G 0 and a new phase rule for open systems), and this may be put in the form of a question: “Do they provide insight into the petrological analyses of those rock systems to which they apply?” We stress the fact that this question is necessarily irrelevant since the petrologist must always replace it with one of higher logical priority, viz. “Is the rock system which I wish to analyze in terms of G 0 and the Korzhinskii phase rule an open system in equilibrium?” If the answer is affirmative, what further insight is necessary? If the answer is negative, the Korzhinskii treatment does not apply. If the answer is in doubt (as it will be most commonly) there is no formalism rooted in the thermodynamics of reversible processes which bears on the problem.