CORRELATION FOR THE THIRD VIRIAL COEFFICIENT USING Tc, PC, DIPOLAR POLARIZABILITY AND MEAN RADIUS OF GYRATION AS PARAMETERS

A new semi-empirical correlation for third virial coefficients of pure non-polar gases and their mixtures has been developed. It has been formulated as a sum of three contributions: two for pair additivity and non-additivity to the simple fluids and one for size and shape effects of the molecules. These contributions have been correlated with theoretically calculated data for argon, krypton and xenon and with an important set of emperimental data on third virial coefficients for 12 non-polar gases, The final correlation has been applied to 21 pure non-polar gases, 3 quantum fluids and 12 binary mixtures of classical and quantum gases. The results have been compared with other available methods. The overall comparison shows that this new method is equivalent or better than those, and that its major advantage is its predictive capability and its better theoretical representation thai should allow, in principle, its extension to more complex fluids.