An equation of state for argon

An analytical equation of state was applied to calculate the thermodynamic properties for argon. The equation of state is that of Song and Mason. It is based on a statistical-mechanical perturbation theory of the hard convex bodies and can be written as fifth-order polynomial in the density. There exist three temperature-dependent parameters: the second virial coefficient, an effective molecular volume, and a scaling factor for the average contact pair distribution function of hard convex bodies. We used Lennard-Jones (12-6) potential for calculation of temperature-dependent parameters. The equation of state has been applied to calculate thermodynamic properties including the vapor pressure curve, the compressibility factor, fugacity coefficient for argon. The agreement with experiment is good.