A model for the excess properties of 1-alkanol+ alkane mixtures containing chemical and physical terms

Abstract

The excess properties of 1-CmH2m+1OH + CnH2n+2 mixtures are described for 2 ≤ m ≤ 12 and 4 ≤ n ≤ 16 using a model with chemical and physical terms. The model is a development of earlier attempts by Stokes et al., Kohler et al., and Gaube et al. It assumes chain association with a distribution of association constants favouring chains of medium length, the existence of cyclic tetramers, a heat of formation of a hydrogen bond of -25 kJ mol-1 (except for smaller values of dimer and trimer), and a volume change of formation of -5 cm3 mol-1. The physical terms contain a configurational contribution calculated after Donohue and Prausnitz, and a residual term calculated with Kehiaian’s model of group surface interactions. The model reproduces the excess properties gE, hE, cPE and vE of numerous systems almost within experimental accuracy, and may thus serve for interpolation between different numbers of m and n. The principal correctness of the chemical terms is corroborated by a n.m.r. investigation on ethanol + cyclohexane and the temperature dependence of vE of ethanol + hexane. © 1989, Walter de Gruyter. All rights reserved.