Total vapour pressures, thermodynamic excess functions and complex formation in binary liquid mixtures of some organic solvents and sulphur dioxide

Abstract

Total vapour pressures at 228, 237 and 250 K are reported for binary liquid mixtures of chloroform, acetone, toluene, m-xylene and mesitylene with sulphur dioxide. The excess Gibbs functions are positive for chloroform + SO₂, negative for acetone + SO₂, and change sign at a composition that depends strongly on temperature for the arene + SO₂ systems. The excess entropy is negative for all systems.

Excess Gibbs functions are also calculated from existing data for mixtures of SO₂ with isobutene, 3-methylbut-1-ene, diethylaniline and ethylene glycol. The excess functions for all systems can be interpreted using association models which involve a self-association constant for sulphur dioxide (component B), a binary association constant, and either a constant describing intermolecular interactions among complexes or a self-association constant for component A.