The basic constraint for any valid expression for local composition, derived by McDermott and Ashton, is shown to be equivalent to the conservation equation used in Flemr's analysis. A similar constraint for local surface fractions is derived. The applicability of quasi‐chemical expressions for local composition or local surface area fractions is extended to different existing (random) models of solutions. Chao's and Kehiaian's treatments appear as special cases. The statistical thermodynamic derivation of UNIQUAC is discussed in the framework of the generalized treatment. A method for solving the quasi‐chemical equations for quaternary systems is described.
No takes yet. Share an insight, caveat, or question.
Panayiotou et al. (1981) studied this question.