Second Virial Coefficients of Argon, Krypton, and Argon-Krypton Mixtures at Low Temperatures

Abstract

Second virial coefficients of argon between 80–125°K, and krypton (105–140°K), have been measured. The experimental values are 5–15% larger in magnitude than those calculated from 12–6 or exp—6 potential functions by the substitution of parameters assigned to describe high‐temperature virial coefficients. Second virial coefficients calculated from the potential‐distance relationship proposed by Guggenheim and McGlashan are within 1% of the experimental values for argon, but are about 4% smaller in magnitude than the measured krypton coefficients. Argon‐krypton mixed virial coefficients have been determined between 105–125°K. These experimental results are best expressed by a 12–6 potential energy parameter combining rule ε₁₂=2ε₁ε₂/ε₁+ε₂.