Correlation of the chemical thermodynamic properties of alkane hydrocarbons

An internally consistent correlation was made of the extant experimental data on the entropy, heat capacity, enthalpy of formation, and isomerization equilibria of alkane hydrocarbons. Of the data selected as reliable, all 41 values of entropy, 98 out of 100 values of heat capacity, 52 out of 54 values of enthalpy of formation, and all 15 values of enthalpy of isomerization from equilibrium data were fit within the assigned experimental uncertainty. Working formulas, tables, and equations are given whereby thermodynamic properties for selected temperatures between 200 and 1500 K can be calculated for any alkane hydrocarbon with a tractably small number of molecular conformations (say ≤34=81). Compounds with more conformations can be included by use of appropriate substitution methods. Values so obtained for the entropy, heat capacity, and enthalpy of formation at 298.15 K are tabulated for all alkanes C3–C10. Variance-covariance matrices from least squares adjustment of constants provide estimates of the reliability of calculated property values. Gaps are noted in the data base that should be filled to permit improved correlations in the future.