The behaviour of fluids of Quasi-Spherical molecules. IV. Concerning Trouton's and Hilderbrand's rules

Abstract

An examination of the theoretical foundations of Trouton's and Hildebrand's rules gives an explanation of the greater generality of Hildebrand's rule. In a group of liquids obeying the principle of corresponding states those with the larger critical volumes V_c have smaller Hildebrand entropies of evaporation. But in many groups of non-polar liquids an increase in V_c is accompanied by a change in the form of the molecular interaction potential (with consequent departure from the principle of corresponding states) and this change can produce a compensating increase in Hildebrand's entropy.