Thermodynamic properties of (an ester + an alkane). XVII. Experimental HmE and VmE values for (an alkyl propanoate + an alkane) at 318.15 K

Abstract

In this article, we record the experimental values of HmE and VmE, obtained at a temperature of T = 318.15 K and atmospheric pressure for a set of 30 binary mixtures comprised of five alkyl propanoates (methyl to pentyl) with six odd alkanes (heptane to heptadecane). The net values obtained for these properties are the result of different effects of the selected compounds on the mixing process. These effects and the variation with temperature are studied. The HmE are positive in all cases and increase with the saturated hydrocarbon chain and diminish with the alkanolic portion of the ester. The variation in VmE is similar to that occurring in the HmE. For the data correlation, a new form of polynomial equation is used in which the variable is the so-called active fraction which, in turn, is a function of the concentration of the mixture, giving acceptable estimations for simultaneous correlations between the values of Gibbs function obtained in the isobaric (liquid + vapour) equilibria and the enthalpies of the mixture, for some of the mixtures studied. The results are explained with the molecular model proposed for (ester + alkane) mixtures. Finally, the application of two versions of the UNIFAC groups contribution method to estimate enthalpies of the mixtures does not give satisfactory results, although the modified UNIFAC gives somewhat better results. © 2005 Elsevier Ltd. All rights reserved.