Calculation on a Corresponding States Basis of the Volume Change on Mixing Simple Liquids

Abstract

There are experimental values of VE (the volume change on mixing) for eight binary liquid mixtures formed from the following substances: argon, krypton, methane, oxygen, nitrogen, carbon, and monoxide. Using a new equation of state data for the pure liquids, VE at zero pressure has been calculated for the eight systems on a corresponding states basis. Since the experimental information for liquid argon is particularly comprehensive, this substance has been taken as establishing the basic reduced-volume-reduced-temperature curve, and the intermolecular energy parameters for the other substances have been adjusted to give the best fit with this curve. The calculations have been made on the one-liquid, two-liquid (or refined average potential), and three-liquid (or separate interaction) models, and for a range of ratios of the intermolecular energy parameters of the two components of the mixture. The one-liquid model generally predicts a VE which is too positive. Of the two- and three-liquid approaches, neither can be said to be superior to the other. Both fail to give reasonable agreement with the experimental VE for the two systems with the most symmetrical molecules, namely argon-krypton and argon-methane.