Thermodynamic properties of (a methyl ester + an n-alkane). II

Abstract

HEm and VEm for six mixtures of {a methyl ester (from ethanoate to heptanoate) + hexane} were determined at the temperature 298.15 K and normal atmospheric pressure. The HEm values were measured directly with a Calvet microcalorimeter, and the VEm values were calculated indirectly from density measurements taken with a vibrating-tube densimeter. The HEm values for all the mixtures were positive over the entire range of mole fractions; however, the VEm values were positive for all the mixtures except those containing methyl hexanoate and methyl heptanoate, whose curves presented sigmoidal forms with VEm < 0 at ester mole fractions >0.641 and >0.136, respectively. The experimental curves were compared with the curves predicted using various theoretical approximations; none of the models, however, yielded good predictions of the VEm values. © 1993 Academic Press Ltd.