An empirical model for calculating second virial coefficients

Abstract

A model for calculating the second virial coefficients of pure compounds and mixtures is proposed. This model derives from a new equation of state which obeys some theoretical constraints and it requires only the molar volume and the vaporization enthalpy at the normal boiling point as input parameters. The new relation is applied to correlate the B values of nearly 70 compounds which represent several molecular types, including strongly associated or dimerizing compounds. Rules are given to generalize the empirical constants of both models in order to predict the B values. The extension to correlate or to predict the second cross virial coefficient is also examined for 20 binary mixtures. The reliability of the proposed model is evaluated by comparison with the Tsonopoulos correlation.