The continuity and family concepts: Useful tools in fluid phase science

Abstract

The concept of a continuity of all types of phase equilibria in fluid binary mixtures and of the corresponding critical phenomena, formulated by us about forty years ago, was supported by systematic measurements on so-called “families” of binary systems. In such a “family” one component (say, e.g., the solvent) is maintained constant (by analogy with the mother or the father) whereas the second component (by analogy with the different children) is varied systematically. Thus sequences of different types of phase behaviour can be obtained. It is the aim of the present contribution to review such families and their interrelations to theoretical classification schemes (such as, e.g., that of Scott and van Konynenburg) and to extend the treatment to mixtures of three and more components.