Thermodynamics of binary liquid mixtures involving hydrogen bromide, hydrogen chloride and xenon

Abstract

The total vapour pressure of the systems hydrogen bromide + xenon and hydrogen bromide + hydrogen chloride have been measured as a function of composition at 195.42 K. The results have been used to estimate the excess Gibbs function G^E. The volume of mixing V^E has been determined for each system at 195.42 K. The HBr + Xe system departs considerably from ideal behaviour, while HBr + HCl is only slightly nonideal. Neither system exhibits an azeotrope at the temperature studied. These results, together with similar data reported previously for the HCl + Xe system (J.C.S. Faraday I, 1975, 71, 1372), are compared with theoretical calculations based on perturbation theory for liquids of nonspherical molecules. Agreement is good for all three systems. The results show that both dipolar and quadrupolar forces for the HCl and HBr molecules have a large effect on the phase diagram, while other types of anisotropic intermolecular forces (overlap, dispersion, induction) appear to have a considerably smaller effect.