Equation of state for compressed liquids and their mixtures from the cohesive energy density

A procedure is presented, based on statistical-mechanical theory, for predicting the equation of state of compressed normal liquids and their mixtures from two scaling constants that are available from measurements at ordinary pressures and temperatures. The theoretical equation of state is that of Ihm, Song, and Mason, and the two constants are the enthalpy of vaporization and the liquid density at the triple point, which are related to the cohesive energy density of regular solution theory. The procedure is tested on a number of substances ranging in complexity from Ar and CO₂ to n-heptane and toluene. The results indicate that the liquid density at any pressure and temperature can be predicted within about 5%, over the range from T_tp to T_c and up to the freezing line. Possible methods of determining the scaling constants are discussed, as well as other possible choices for scaling constants.Paper dedicated to Professor Joseph Kestin.