Fluid phase behavior of water — Non polar mixtures Concentration Fluctuations in H 2O- X ( X = H2, He, Ar)

Abstract

The concentration fluctuations, S cc(0), of H 2O- X ( X = H 2, He, Ar) binary mixtures under pressure are calculated using a thermodynamic perturbation theory based on polarizable hard spheres of equal diameter. This work is specifically concerned with the behaviour of S cc(0) at thermodynamic states undergoing phase separation as a function of concentration. The mean field character of the theory used in this work means that S cc(0) → ∞ at those concentrations where it finds points on the spinodal curve. In all the cases studied the tendency to homo coordination is already present at low concentrations. However, the sharp increase of S cc(0) as it approaches the spinodal curve is sudden and over a very narrow range.