Excess molar heat capacities and enthalpies for 1-alkanol + N-alkane binary mixtures. New measurements and recommended data

Abstract

Excess molar heat capacities at constant atmsopheric pressure C p E have been determined at 298.15 K as a function of the alcohol mole fraction x, for the following binary mixtures : ethanol + n-hexadecane, 1-butanol + n-decane, and 1-hexanol + n-hexane. The instrument used was a Picker flow calorimeter. The densities p for these mixtures at the same pressure and temperature were measured with a vibrating-tube densimeter ; the corresponding molar excess volumes V E were calculated therefrom. For the same mixtures as well as for the two other mixtures methanol + n-heptane and ethanol + n-heptane a complete literature search has yielded a selection of both the excess molar heat capacities and enthalpies H E. Several selected sets of data have been critically analyzed in terms of quality of measurements and precision. The best sets of data have been combined together and, also whenever possible, with our present experimental data to produce recommended data sets of the two calorimetric properties for the five binary mixtures, then considered as key-systems. In the course of this work particular attention was paid to keep data points in the whole concentration range especially in the dilute regions. Finally for each above mixture the recommended values of C E p and H E have been fitted accordingly with the same type of smoothing equation.