Molecular shape and orientational order. Effects in the energy of cavity formation in liquids

A recently proposed method for calculating the energy of cavity formation in liquids is presented in which the cavity formation process is described as work against the surface forces of the solvent, at the microscopic scale. The energy involved in the cavity formation process is, on the other hand, viewed as a strictly interaction potential energy and the reference cavity, which has the size and the shape of the space occupied by each molecule in the liquid, is considered as having short-range orientational order characteristic of the pure liquid. The method is successfully applied to binary alkane mixtures at infinite dilution whose components have different chemical structure (linear, cyclic and branched alkanes). The importance of the changes in the molecular order of the solute and the solvent occuring in the mixing process is emphasized.