Thermodynamic study on the sublimation of 1,2-diphenylethane and of 3-phenylpropiolic acid

Abstract

The Knudsen mass-loss effusion technique was used to measure the vapour pressures at different temperatures of the following crystalline compounds: 1,2-diphenylethane (bibenzyl), between T= 289.16 K and T= 303.20 K, and of 3-phenylpropiolic acid between T= 329.15 K and T= 343.15 K. From the temperature dependence of the vapour pressure, the standard molar enthalpies of sublimation at the mean temperature of the experimental range were derived by the Clausius–Clapeyron equation. From these results the standard, po= 105Pa, molar enthalpies, entropies, and Gibbs energies of sublimation at T= 298.15 K, were calculated: