A corresponding‐states correlation for higher molecular‐weight liquids

A corresponding‐states correlation for the liquid‐state properties of higher molecular‐weight substances is presented which contains as reducing parameters the readily measurable (and correlatable) energy vaporization and van der Waals volume instead of the often inaccessible critical constants. One additional parameter characterizing molecular flexibility is introduced. A single curve of the new reduced density ρ* vs. the new reduced temperature T * is shown to represent the atmospheric‐pressure‐density‐temperature relations of paraffinic, naphthenic, and aromatic hydrocarbons with 10 or more carbon atoms per molecule to within ±1% between their melting and their atmospheric boiling points. The reduced surface tension is shown to be a unique function of ρ± for many compounds, thus permitting prediction of surface tension over wide ranges of temperature. The heat‐capacity difference between liquid and vapor proved to be easily correlatable with ρ±. Finally the compression of numerous hydrocarbons proved to be well correlated in terms of T *, ρ±, and P *. Extensive group data for V w and E ° have been assembled in the appendix in order to enable others to use the proposed method without effort.