Corresponding states correlations with potential between functional groups for thermodynamic properties of liquid n- and i-alkanes

For liquid n-alkanes, C1 to n-C21 and i-alkanes, i-C4 to i-C10 the interactions between the molecules are described with the use of potentials between the functional groups (inter-group potentials). The molar volume of liquid in saturation and the vapor pressure are correlated in the corresponding states method well and the surface tension is correlated satisfactorily with the use of the inter-group potential parameters and distance correction parameters. The correlations are better than those with the use of intermolecular potential parameters without the use of the inter-group potentials. The distance correction parameters can be fitted by functions of the location and the number of the groups in the molecule. The thermodynamic properties of the heavier liquid n-alkanes, n-C22 to n-C30, n-C32 and n-C36, which are not used for the parameters evaluation, can be predicted satisfactorily in the corresponding states method with the inter-group potential parameters and the distance correction parameter functions.