Surface tension of isomers of pure hydrocarbons: a method for estimation and prediction

A new method to estimate and predict surface tension in the full liquid-state temperature range for isomers of pure hydrocarbons has been developed. The method requires as input parameters the surface tension value corresponding to the linear or normal member of a given hydrocarbon homologous series, modified by an empirical parameter here proposed for each isomer under study. This in turn is calculated using molar volume and solubility parameter values for both the normal and the isomer hydrocarbon. This new method was used to calculate surface tension values for 56 isomers of n-alkane and four isomers of the 1-alkene homologous series in the range 253–373 K. The average error obtained from a comparison between experimental and calculated surface tension values for 497 points of the 60 isomers considered was only 1.5%. The developed method may also be used to obtain surface tension data with high reliability above and below the temperature range for which experimental data are available for both normal and isomer hydrocarbons.