Using the Vapor Pressure of Pure Volatile Organic Compounds to Predict the Enthalpy of Vaporization and Computing the Entropy of Vaporization

Abstract

The objective of this investigation was to develop a vapor pressure (VP) acquisition system and methodology for performing temperature-dependent VP measurements and predicting the enthalpy of vaporization (ΔHvap) of volatile organic compounds, i.e. VOCs. High quality VP data were acquired for acetone, ethanol, and toluene. VP data were also obtained for water, which served as the system calibration standard. The empirical VP data were in excellent agreement with its reference data confirming the reliability/performance of the system and methodology. The predicted values of ΔHvap for water (43.3 kJ/mol, 1.0%), acetone (31.4 kJ/mol; 3.4%), ethanol (42.0 kJ/mol; 1.0%) and toluene (35.3 kJ/mol; 5.4%) were in excellent agreement with the literature. The computed values of ΔSvap for water (116.0 J/mol∙K), acetone (95.2 J/mol∙K), ethanol (119.5 J/mol∙K) and toluene (92.0.J/mol∙K) compared also favorably to the literature.