Thermodynamic and physical behavior of binary mixtures involving sulfolane II. Viscosity, dielectric constant, solid + liquid phase diagram of mixtures of benzene + sulfolane

Abstract

Excess functions, H ≠E, S ≠E, and G ≠E, for activation of viscous flow, as well as the deviations from ideality of dielectric constants for sulfolane + benzene have been determined; slight negative deviations from ideality for both are observed with a minimum at mole fraction x ≈ 0.5. The solid + liquid phase diagram is presented and activity coefficients of sulfolane and benzene are calculated from initial freezing temperatures of benzene up to the eutectic composition. The phase diagram precludes the existence of definite compounds between the two components; moreover, the viscosity and dielectric constant measurements appear to eliminate the occurrence of strong interactions between unlike molecules. Deviations from ideality are, therefore, to be related rather to structural effects and constraints on the shapes of the molecules in the mixtures.