Thermodynamics of liquid binary (alkanenitrile–alkane) mixtures. Part1.—Experimental excess molar volume at 298.15 K and its interpretation with the Prigogine–Flory–Patterson theory

Abstract

Density measurements have been made by means of a vibrating tube densitometer, at 298.15 K, over the whole composition range for 25 binary liquid mixtures of propanenitrile, butanenitrile, pentanenitrile and hexanenitrile with several different hydrocarbons. Values of the molar excess volume, V^E, were derived and the results show a regular pattern of behaviour for each of the four sets of binary system. For a given alkanenitrile, the magnitude of V^E increases with the hydrocarbon chain length and also for a given hydrocarbon, V^E decreases with the chain length of the nitrile. The Prigogine–Flory–Patterson theory was applied to analyse the experimental behaviour by calculating three different contributions to V^E, i.e. interactional, free volume and internal pressure. The theory is capable of reproducing the main features of the experimental V^E results by using a fitted binary interaction parameter.