Collect. Czech. Chem. Commun. 1989, 54, 1446-1463

A modification of the Redlich-Kwong-Soave equation of state and the determination of its parameters on the basis of saturated vapour pressures and second virial coefficients of pure substances

Petr Voňka, Pavel Dittrich and Josef P. Novák

Department of Physical Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


The temperature dependence of parameter a = a(Tr) of the Redlich-Kwong-Soave equation of state was modified. To calculate the corresponding individual parameters, an effective algorithm applying the Newton method was proposed. The parameters were determined for 60 substances, and the new modification correlates saturated vapour pressures from the values of pr = 0.001 to pr = 1.0 with the accuracy which is usually better than 0.2% and is comparable with that attained in terms of the Wagner equation. The modification proposed is utilized above all when applying the equation of state to the calculation of vapour-liquid equilibrium.