Thermodynamic properties of (ethylbenzene + an alkane or + an alkyl ethanoate): experimental H_m^E and V_m^E values

Abstract

In this work, we present the experimental values of excess molar enthalpies, , and excess molar volumes, , 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 + C _n H_{2 n +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 . The aromatic mixtures with alkyl ethanoates, C₆H₅C₂H₅ + CH₃COOC _v H_{2 v +1}, show a different behaviour. In this case, both the diminish quasiexponentially with the increase in v, resulting in < 0 for mixtures with v = 4, and sigmoidal when v = 3. The rise in temperature produces a . 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 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.

Keywords:

• excess enthalpy
• excess volumes
• alkane
• ethylbenzene
• ethanoates
• UNIFAC

Acknowledgement

The authors thank the Ministerio Educación y Ciencia of Spain for funding this work via project CTQ2006-12027.