Thermodynamic Investigation of the Azeotropic Binary Mixture Water + n-Propanol

Molar heat capacities of the azeotropic mixture in the binary system {water ( x = 0.568) + n -propanol ( x = 0.432)}were measured with an adiabatic calorimeter in the temperature range from (80 to 320) K. The functions of the heat capacity with respect to the thermodynamic temperature were established. A glass transition was observed at 102.037 K. The solid−liquid-phase transition of the azeotropic mixture took place in the temperature range from (237.075 to 262.424) K. The corresponding enthalpy and entropy of the solid−liquid-phase transition were calculated to be 5.869 kJ·mol -1 and 22.73 J·K -1 ·mol -1, respectively. The thermodynamic functions and the excess thermodynamic functions of the azeotropic mixture relative to a temperature of 298.15 K were derived on the basis of the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.