Dependence of hydrophobicity of apolar molecules on their molecular volume

Cavity size is the primary determinant of the partition coefficient (P) of apolar solutes between octanol and water. Although the energy of cavity formation would be expected to be related to cavity area, older methods of area calculation give a poorer correlation with log P than does volume. Apolar solutes clearly fall into two classes based on their log P/volume relationship, the distinction possibly being whether the solute exposes mostly hydrogen atoms or unbonded electrons.