Estimation of the Thermodynamic Properties of Hydrocarbons at 298.15 K

Abstract

An estimation method developed by S. W. Benson and coworkers, for calculating the thermodynamic properties of organic compounds in the gas phase, has been extended to the liquid and solid phases for hydrocarbon compounds at 298.15 K. The second order approach which includes nearest neighbor interactions has been applied to the condensed phase. A total of 1311 comparisons are made between experimentally determined values and those calculated using additive group values. Of the 559 comparisons given for the enthalpy of formation (Δf H°) in the gas, liquid, and solid phases, the average difference (residual), without regard to sign, is 2.6 kJ/mol. The average differences for 390 comparisons for the heat capacity (C○p) and 352 comparisons for the entropy (S°) in the three phases are 1.9 and 2.3 J.mol⋅K, respectively. The good agreement between experimental and calculated values shows that the Benson group additivity approach to the estimation of thermodynamic properties of organic compounds is applicable to the liquid and solid phases as well as the gas phase. Appendices provide example calculations of the thermodynamic properties of selected hydrocarbon compounds, total symmetry numbers, and methyl repulsion corrections. Most of the 144 references listed offer an indication of the activity in the development of estimation methods for calculating thermodynamic properties since 1931.