Relationship between the heat capacity change on vaporization of normal and branched alkanes and the vaporization enthalpy and its prediction as a function of temperature

Highlights: • Relation between enthalpies and heat capacities of vaporization of alkanes was analyzed. • A way to estimate vaporization enthalpy as a function of temperature was proposed. • Vaporization enthalpies of 192 alkanes were calculated and compared with literature. In the present work, the relationship between the difference of the heat capacities of the liquid and ideal gas and intermolecular interaction energy in alkanes was investigated. The vaporization enthalpy at 298.15 K was considered as a measure of intermolecular interaction energy. For 40 alkanes linear correlation between the above quantities was revealed with a root mean square deviation (RMS) of 3.5 J·K⁻¹·mol⁻¹, regardless of branching. Using this correlation and group-contribution-derived vaporization enthalpies at 298.15 K, the vaporization enthalpies of 192 alkanes at elevated temperatures were calculated and compared with 317 literature values. RMS equaled 1.7 kJ·mol⁻¹, being competitive with experimental techniques.