Size dependence of the solvation free energies of large solutes

The solvation Gibbs free energy of linear molecules is shown to be a linear function of the length, or number of units, of the molecule when this length exceeds the correlation length of the solute due to the solvent. For large molecules in simple solvents, the solvation Gibbs energy, in leading order, scales as the solute volume, not the solute surface area, as might be expected. The solvation Gibbs energy, as determined from experimental measurements on solute concentrations in coexisting phases, needs no correction due to solute-solvent size ratio. A critique of a recent assertion to the contrary is presented.