Some Properties of van der Waals' Liquids

Abstract

A theoretical consideration of the volume of a van der Waals' liquid suggests some new rules, comparable to that of Trouton, relating coefficients of expansion and compressibility to heats of vaporization. According to the simplest and most reliable of these new relationships, the product of the coefficient of cubical expansion and the heat of vaporization, αΔHv, is the same for many liquids and equal to about 10 cal./deg. It is further shown that at a given temperature, ΔHv2β/V is also constant where β is the compressibility and V the volume of the liquid. Certain corollary rules are derived by combining the above two with each other and with Trouton's law. These new rules should prove of some value in estimating compressibilities and heats of vaporization from coefficients of expansion.