Thermodynamic properties of (ethylbenzene plus an alkane or plus an alkyl ethanoate): experimental Hm(E) and Vm(E) values

Abstract

In this work, we present the experimental values of excess molar enthalpies, HEm, and excess molar volumes, VEm, for a set of mixtures composed of ethylbenzene with several alkanes, from heptane to hexadecane, and the first four alkyl ethanoates. In all cases, measurements were made at the two temperatures of 298.15 and of 318.15 K. The mixtures of C6H5C2H5 + CnH2n+2 present endothermic effects that increase quasilinearly with n, and expansive effects that also increase with n, but quasiexponentially. The influence of temperature on these mixtures produces thermal indices (δHEm/δT)p,x < 0 and (δVEm/δT)p,x < 0. The aromatic mixtures with alkyl ethanoates, C6H5C2H5 + CH3COOCvH2v+1, show a different behaviour. In this case, both the HEm and the VEm diminish quasiexponentially with the increase in v, resulting in HEm < 0 for mixtures with v = 4, and sigmoidal when v = 3. The rise in temperature produces a (δHEm/δT)p,x > 0 and (δVEm/δT)p,x > 0. In all cases, the experimental values were treated with a suitable polynomial equation that can simultaneously correlate the excess properties with liquid-vapour equilibria data. Finally, a prediction of the HEm values was made with two versions of the UNIFAC group contribution model, although it was necessary to recalculate parameters corresponding to the CH2/ACCH2 and COOC/ACCH2 interactions for the groups of mixtures studied in the version of Dang and Tassios (Ind. Eng. Chem. Des. Dev. 25, 22 (1986)), to obtain acceptable estimations. © 2009 Taylor & Francis.