DETERMINATION OF MIXED VIRIAL COEFFICIENTS.

Abstract : An experimental apparatus was constructed and developed and with it the interaction second virial coefficients were measured from -125C to 50C in 25C increments for the following systems: N2-Ar, Ar-H2, Ar-He, Ne-Ar, N2-H2, N2-He, Ne-N2, H2-H3, Ne-H2 and Ne-He. The excess and interaction second virial coefficients were determined usually within 0.1 cc/mole corresponding to an error in the ration of pressure change after mixing to P of 0.000005, by measuring the pressure change of mixing two pure gases at constant temperature and volume. This precision corresponds to about one part in 200,000 for conventional PVT experiments. The comparison between experimental values and those calculated by the Kihara potential was considered good at the higher temperatures and fair to poor at the lower temperatures where it was as much as 8 cc/mole. In the temperature range of -125C to 50C, the excess quantity, E, was empirically correlated to the absolute temperature by the relation, E = aT to the b power, where the value of b was essentially the same for most of the binary mixtures. (Author)