Prediction of excess properties for liquid mixtures: results from perturbation theory for mixtures with linear molecules

Abstract

A Weeks—Chandler—Andersen type perturbation theory is used to predict excess properties of liquid binary mixtures of spherical and linear dumbbell-like molecules and mixtures with two dumbbell-like components. The calculations are improved by the introduction of a new blip formalism. A combining rule used previously for mixtures of spherical molecules is extended to mixtures with nonspherical ones and criteria are given as to when reasonable results can be expected. This is demonstrated for 20 binary mixtures. It is also shown that fitting the unlike interaction to one excess property ( g E or h E) always gives good results for the other excess properties, provided that the electric moments are not too big. Finally, it is shown for the mixture Xe + C 2H 6, that the perturbation theory can reproduce the temperature variation of the excess properties almost within experimental error.