The relation between the heat and entropy of solution

Abstract

(1) The entropies of solution of four solutes in acetone and seven solutes in ethyl alcohol have been determined at 25 °C.(2) The values in acetone extend the linear relation, between the entropy and heat of solution from All = 4 to 10 k -cals. The values in alcohol are appreciably higher than those in acetone for the same heats of solution.(3) It is pointed out that all the entropies of vaporisation of solutes from non- associated solvents now available, as well as those of pure non- associated liquids themselves, approximate to a single linear relation between the entropy and heat of vaporisation. This relation is shown to be equivalent to the known fact that the Trouton ratio (entropy of vaporisation at the boiling point) increases slightly with the boiling point. Dilute solutions and pure liquids thus obey the same relation.(4) The abnormally high entropies of vaporisation of solutes from associated liquids are connected with the abnormal surface entropies of cavities in those liquids, indicated by deviations from the Ramsay -Eötvos relation.