EXCESS VOLUMES AND GIBBS FREE-ENERGIES OF MIXTURES CONTAINING ALKANENITRILES

Excess volumes, V(E), by means of a vibrating-tube densimeter, and Vap or-Liquid equilibria, by head-space gas-chromatographic analysis of th e equilibrated vapour phase directly withdrawn from equilibration appa ratus, of binary mixtures containing n-alkanenitriles with n-alkanes o r cyclohexane, were determined at 298.15 K. Measurements of the test m ixtures, ethanol + cyclohexane were also made. Excess molar Gibbs free energies, G(E), for the examined mixtures were obtained by a least - squares treatment of the equilibrium x, y results. The V(E) and G(E) v alues are positive for all the systems. The steric effect exerted by t he alkyl groups adjacent to the CN group results in a regular decrease of the G(E) with increasing the number of alkyl groups in the alkanen itrile.