Linear relationships between the heat, free energy, and entropy of solvation

Abstract

(1) An efficient method has been devised for the determination of the free energy of solvation referred to the vapour as standard state (RT log p/TT) or to the liquid (RT log p /p °N) as reference standard.

(2) The entropy of solvation has been evaluated by measuring RT log p/N at two temperatures (25 °C and 35 °C).

(3) The partial vapour pressures, at 25 °C and 35 °C, have been measured for some aliphatic alcohols in water; and for acetone, benzene, carbon disulphide, chloroform, diethyl ether and ethyl acetate in each other.

(4) The free energy, heat and entropy of solvation have been calculated (a) with reference to the vapour at unit pressure (1 mm. Hg) (b) in terms of the Ostwald Coefficient.

(5) Linear relationships between the three thermo- dynamic functions are found for the alcohol and alkyl halide series in water.

(6) The entropy variations are related to the par- tial molar volumes for the alcohol series.

(7) Linear relationships,named A and B heretofore, exist, for the organic solutions, between the functions, evaluated in concentration unite; and the relative size of the solute molecule is considered the main factor in these cases.