Dissociation Treatment of Condensing Systems—IV

The more exact dissociation theory of Part II, is applied to eighteen different gases and vapors, ranging in molecular weight from H2 to Xe. Interaction energies per molecule in clusters formed during condensation of the saturated vapors are found as functions of temperature. From the differences between surface energy and measured surface tension, which remain finite at Tc, estimates are made of the numbers of heavy clusters maintained in the saturated vapor over the liquid surface, also as functions of temperature. In the case of eight vapors, the theory predicts measurable differences between the two critical points, Tc at which the meniscus blurs, and Tr at which the densities equalize; the largest differences being for water, 6.5°K; methyl alcohol, 5.1°K; and nitrous oxide, 4.1°K. True critical volumes at Tr are calculated.