A van der Waals approach to the entropy convergence phenomenon

The van der Waals approach for the excluded volume effect is used to calculate the thermodynamics of cavity creation in a liquid. By using the experimental density of c-hexane, benzene and water and a temperature independent hard sphere diameter for solvent molecules, the van der Waals approach leads to the following results: (a) the values of the work of cavity creation show a linear decrease in the two organic solvents, but a parabolic temperature dependence with a maximum around 170degreesC in water; (b) the cavity entropy changes are positive and practically independent of temperature in the two organic solvents; (c) the cavity entropy changes in water are large negative at room temperature and then increase showing the convergence phenomenon at 160degreesC. Therefore, the experimental density of solvents at each temperature and the hard sphere diameter of solvent molecules considered to be temperature independent are sufficient to distinguish water from c-hexane and benzene and to reproduce entropy convergence.