SOLVATION THERMODYNAMICS OF GAS SOLUBILITY AT SUB-CRITICAL AND NEAR-CRITICAL CONDITIONS

The recently developed formalism for describing the solute-induced eff ect in dilute near-critical mixtures is extended to fluids composed of anisotropic molecules through the statistical mechanical interpretati on of the derivative (partial derivative P/partial derivative x(2))(T, rho)(infinity) whose critical value is the Krichevskii parameter. Rigo rous expressions for Henry's constant and the solute distribution fact or along the orthobaric curve are derived in terms of the volumetric a nd entropic solute-induced local effects, and the quasi-linear behavio r of their orthobaric density dependence away from the solvent's criti cal point is rationalized. The formalism is illustrated with integral equation calculations of the orthobaric density dependence of several solvation thermodynamic quantities for an infinitely dilute volatile s olute in near-critical solutions of hard-sphere Yukawa fluids.