Intermolecular model potentials and virial coefficients from acoustic data

Abstract

A simple method is presented for the determination of model two- and three-body intermolecular potentials from acoustic data. The method is applied to argon, nitrogen, methane, ethane and propane. For argon, the second, third and fourth volumetric virial coefficients from the model potentials are compared with values determined in direct experiments. Second virial coefficients are shown to be in very good agreement with experiment. For the  third volumetric virial coefficients, significant discrepancies are noted in the region of the maximum in the function. There are no experimental data for a direct comparison of the fourth volumetric virial coefficients presented here; however, because in a previous work, it was shown that fourth acoustic virial coefficients calculated from a similar method agreed with values determined in direct experiment, we argue that the values presented here are accurate.

Key words: Equation of state, virial coefficients, speed of sound, intermolecular potentials