INVESTIGATION OF LIQUID-VAPOR-EQUILIBRIUM USING AN INTERPOLATION EQUATION OF STATE

An interpolation equation of state is proposed, which changes into the equation of state for ideal gas in the case of low density, and into the Mie-Gruneisen equation in the case of high density. Its interpolat ion properties are governed by the pressure dependence of the Gruneise n coefficient in the rarefaction region, which includes two arbitrary constants. The preassigned input parameters of the equation include th e density, Debye temperature, Gruneisen coefficient, and the heat capa city in the solid phase, statistical sum of atoms in the gas phase, as well as the critical density, pressure, and temperature. This equatio n of state describes the totality of the experimental data on the coex istence curves and saturation pressure for cesium and mercury, i.e., t he metals for which the most complete experimental data are available. The coexistence curve is plotted for a group of nonmetallic substance s that satisfy the law of corresponding states. Agreement is reached f or aluminum, lead, and copper with respect to the saturation pressure in the low-temperature region, and theoretical coexistence curves are plotted.