CRITICAL PHENOMENA IN MIXTURES .1. THERMODYNAMIC THEORY FOR THE BINARY CRITICAL AZEOTROPE

In this series of papers we provide new results related to critical phenomena in binary mixtures particularly with regard to the phenomenon of critical azeotropy. In Part I we carefully develop a set of necessary and sufficient conditions guaranteeing the existence of critical azeotropy in these mixtures. The sufficiency conditions are particularly useful for determining whether or not a critical azeotrope exists in a system, without having to actually find this point itself, typically a difficult experimental problem. Classical critical exponents of various thermodynamic properties along various paths are determined for the critical azeotrope. These are compared to the analogous situation near a pure fluid critical point in a dilute binary mixture. Both situations display analogies as well as differences that are discussed at some length. In Part II we concentrate upon describing interesting synergistic solvation effects in these systems using many of the results presented in Part I.