Apparent Molar Heat Capacities and Apparent Molar Volumes of Aqueous 1,1,1,3,3,3-Hexafluoroisopropanol at Different Temperatures

Abstract

Specific heats and apparent molar heat capacities of aqueous 1,1,1,3,3,3-hexafluoroiso- proanol (HFIP) have been determined at temperatures from 20.0 to 45.0°C using micro differential scanning calorimetry in the molality range of 0.06741 to 1.24053 mol-kg^{− 1}. Densities and apparent molar volumes have also been determined for aqueous HFIP at temperatures from 10.3 to 30.0°C using digital densimetry in the molality range of 0.04009 to 0.67427 mol-kg^{− 1}. The results of these measurements have been used to calculate the following partial molar quantities and temperature derivatives for aqueous HFIP as a function of temperature: C_p,2,m°, (∂C_p,2,m°/∂T)_p, (∂²C_p,2,m°/∂T²)_p, V_2,m° and (∂V_2,m°/∂T)_p. The contribution of the — F atom to the partial molar heat capacity and volume has been calculated. The results have been explained in terms of structural changes in water in aqueous HFIP solution. The results obtained in this work contain essential information needed for the development of an equation of state for this system, when used in combination with other thermodynamic properties of aqueous HFIP.