Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

This work presents the measurements of HEm and V Em , obtained at a temperature of T ? 318:15 K and atmospheric pressure for a set of 30 binary mixtures composed of five alkyl ethanoates (methyl to pentyl) with six odd n-alkanes (C7 to C17). The results show that the mixing processes are endothermic in all cases, with regular increases in HEm with the molecular weight of the saturated hydrocarbon and diminishing with the alkanolic part of the ester. The change in V Em is also regular and similar to that of HEm. For data correlation, a new form of polynomial equation is used. In this, the so-called active fraction is used as a variable which, in turn, depends on the concentration of the mixture, giving acceptable estimations of the Gibbs function obtained in the isobaric (liquid+ vapor) equilibria for some of the mixtures studied. Finally, a molecular model which interprets the behavior of mixtures of alkyl ethanoates + n-alkanes and the results of residual quantities is proposed. To these binary systems some group contribution models are applied. A modified version of the UNIFAC model gives satisfactory results for enthalpies.