Vapour-liquid equilibrium and excess free energies for benzene + dioxan and carbon tetrachloride + dioxan systems

Abstract

This paper deals with the isothermal total vapour pressure measurements on the systems benzene + dioxan and carbon tetrachloride + dioxan in the temperature range of 22–40°C and over the whole composition range. The activity coefficients and the excess Gibbs free energies are evaluated at 25, 30 and 40°C. For both the systems the excess entropies are negative, suggesting an ordering in the solution due to a solute-solvent specific interaction. The excess free energies of complexing are calculated on the basis of an ideal associated solution model with species A, B, AB and AB₂ in mutual equilibrium and using for reference, the excess free energies of the system cyclohexane + dioxan. The calculated excess free energies agree with the observed results.