THE VIRIAL-COEFFICIENTS OF 5 BINARY-MIXTURES OF FLUORINATED METHANES AND ETHANES

We have made new measurements of the gas-phase PVT surface of five bin ary mixtures of hydrofluorocarbons (HFCs) in a Burnett/isochoric appar atus. The components chosen all have moderate to large reduced dipole moments. We present PVT data, derived mixture virial coefficients, cro ss second virial coefficients, and binary interaction parameters for t hese systems, and we compare the results with a recently published mod el for calculating second and third viral coefficients of polar gases and their mixtures. That model accounts for the polar nature of the mo lecules with a term containing the reduced dipole moment, mu(R), and i t contains mixing rules for the substance-specific parameters needed t o calculate the second and third cross virial coefficients. The model and data are in satisfactory agreement, and the model can be used to g reatly extend the useful range of the limited set of data.