The Dieterici alternative to the van der Waals approach for equations of state: Second virial coefficients

Historically, the development of equations of state for fluids has almost invariably followed the lead of the van der Waals equation by simply adding together contributions from intermolecular repulsion and attraction. Recently an alternative approach, first suggested by Dieterici (Ann. Phys. Chem. Wiedemanns Ann.,1899, 69, 685), has been revised (R. J. Sadus, J. Chem. Phys., 2001, 115, 1460) with the benefit of modern developments in equations of state. In contrast to the traditional van der Waals-type equations of state, the Dieterici approach results in an equation of state that is the product of a repulsive term with an exponential attractive term. This formulation significantly enhances the accuracy of the prediction of vapour–liquid equilibria, particularly in the vicinity of the critical point. In this work, the ability of the equation to predict second virial coefficients is investigated. A comparison is also reported with traditional van der Waals-type equations of state. The results indicate that the Dieterici approach yields superior prediction of the second virial coefficients.