Calculation of Excess Entropy for Binary Liquid Mixtures by the NRTL and UNIQUAC Models

Isothermal excess entropy data for 23 binary liquid mixtures were calculated using the excess Gibbs energy and excess enthalpy correlations obtained from the local composition models of NRTL and UNIQUAC. The mixtures include highly nonideal, associating, and partially miscible systems. Temperature-dependent parameters of the models were used in the calculations. The experimental data of excess Gibbs energy and excess enthalpy, which were base of excess entropy data, covers the temperature range of 288.15–358.15 K. The average absolute relative deviations of the excess entropy data calculations were obtained as 7.34 and 8.51% for the NRTL and UNIQUAC models, respectively. Excess entropy data at isobaric conditions were also calculated using excess heat capacity data for eight binary liquid mixtures in the range of 238.15–318.15 K. Temperature-dependent parameters estimated directly from excess heat capacity data were used in the calculations which gave the average absolute relative deviations of 10.91 and 12.76% for the NRTL and UNIQUAC models, respectively.