Vapor pressures, molar enthalpies of sublimation, and molar enthalpies of solution in water of 5-(trifluoromethyl)uracil

Vapor pressures, enthalpies of sublimation, enthalpies of solution at infinite dilution, and densities of the aqueous solutions of crystalline 5-(trifluoromethyl)uracil were determined. Vapor pressures and enthalpies of sublimation were measured by the Knudsen effusion method. The heats of solution in water were determined at 298.15 K over the range of concentrations of 0.495 to 0.948 mmol(.)kg(-1) by using an isoperibol solution calorimeter. The molar enthalpy of hydration was calculated by subtracting the estimated molar enthalpy of sublimation and the molar enthalpy of solution. Densities of the solutions were measured with an Anton Paar DMA 60/602 digital densimeter, and the partial volume was estimated. The purity of the substance was determined using a DSC 910 DuPont differential scanning calorimeter with a Thermal Analyzer 1090. The values of the enthalpy of interaction and the enthalpy of cavity formation were calculated.