Correlation between Molecular Sizes of Pure Compounds: Application in Surface Tension Prediction Based on Scaled Particle Theory

In this paper, molecular diameter for various pure compounds are estimated by seven methods, in which three diameters are based on scaled particle theory (SPT) and the others are obtained from actual molecular volumes assuming hard sphere shape for molecules by using Bondi, Edward and Van der Veen methods. The seventh one is obtained from a relationship between molecular volume and parachor. Correlation among seven types of molecular sizes for pure components is reported. Calculated diameters are used to prediction surface tension of 108 pure compounds based on SPT. Calculation results show that the hard sphere diameter which is obtained from reported correlations can be used for estimation of pure substances surface tension with good accuracy.The absolute average deviation percent for surface tension prediction of pure fluids with different correlations is 1.3%, 11.26%, 11.52%, 32.42%, 14.62% 12.16% and 1.95%.