Virial Coefficients of Ethane from a Quadrupolar Site-Site Potential Function

Abstract

A procedure based on a site-site pair potential function, combined with the triple-dipole term, was used to determine the second and third virial coefficients of linear ethane. The parameters in the two-body potential were determined in a fit to experimental second acoustic virial coefficients; no other data were used. The three-body strength coefficient was determined in a fit to speed-of-sound data using isotropic two-body and three-body potentials. The resulting potential parameters reproduced second acoustic virial coefficients and predicted second volumetric virial coefficients of ethane to within an absolute error of 0.5 cm3 mol-1 . The third volumetric virial coefficients were predicted to within an absolute error of 250 cm6 mol-2 . Third acoustic virial coefficients of ethane predicted with the procedure are in good agreement with experiment only at temperatures above about 240 K; below this temperature the two sets of values are inconsistent.