A new approach to substance-dependent three-parameter cubic equation of state

An alternative four-parameter cubic equation of state (CES) and a new form for a temperature dependent coefficient alpha(T-r) of the attractive energy parameter were examined. As a consequence a three-parameter CES is propose d. A critical reduced volume beta(c), an apparent critical compressibility factor zeta(c), and the coefficient alpha(T-r) are compound-specific. The a bilities to describe the vapour-liquid equilibrium for sixteen representati ve pure compounds and p, nu, T behaviour along critical isobar for six sele cted compounds are reported. For the best known CES the percentage deviatio ns of the vapour pressure, saturated volumes, and densities above critical temperature on the critical isobar are compared.