Generalized van der Waals theory. XI. Gas solubility in simple fluids

Abstract

The generalized van der Waals theory of mixtures is applied in the low solute concentration limit to the calculation of the Henry's law constant K_H, the partial molar enthalpy ΔH₅, and the partial molar volume V2. Several versions of the theory are used. Between-species interactions are taken to obey Lorentz-Berthelot rules. Comparison with experiment and earlier theory includes Ar, C₆H₆ and CCl₄ solvents and a number of solute species. At the lowest level of theory simple analytical expressions for K_H, ΔH₅ and V₂ are obtained. The accuracy is semiquantitative with ΔH₅ most in error. The accuracy is improved by allowing for the temperature and density dependence of the effective hard-sphere diameter and the density dependence of the excluded volume. The linear and bilinear mixing rules for the excluded volume are compared and the former found preferable. No experimental parameters (beyond accepted LJ(12-6) parameters) are used.