Thermodynamic investigation of the binary system of ethanol + benzene

Abstract

The molar heat capacity of the binary system ethanol + benzene was measured by an adiabatic calorimeter in the temperature range from 80 to 320 K. The glass transition and phase transitions of the mixture were determined based on the curve of the heat capacity with respect to temperature. The glass transition occurred at 97.536 K, the enthalpy and entropy of the glass transition were calculated to be 1.796 kJ mol −1, 18.414 J mol −1 K −1, respectively. The phase transitions took place in temperature ranges 115.875–128.400, 146.778–159.015 and 256.645–274.981 K corresponding to the solid–solid phase transition of ethanol, solid–liquid phase transition of ethanol and solid–liquid phase transition of benzene, respectively. The corresponding enthalpies and entropies of the phase transition were calculated to be −1.266 kJ mol −1, −10.745 J K −1 mol −1; 2.166 kJ mol −1, 13.818 J K −1 mol −1; 5.390 kJ mol −1, 19.856 J K −1 mol −1, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.