FLUCTUATIONS IN AQUEOUS-SOLUTIONS OF SOME HYDROPHOBIC SOLUTES

The entropy fluctuation in liquids and solutions is most conveniently normalized to the coarse-grained volume. Hence, [(Delta S/V)(2)] = RC(p)/V-m(2) and [(Delta S/V)(Delta N/N)] = RT alpha(p)/V-m. It was shown to be useful if the response functions, C-p, kappa(T) and alpha(p), and the fluctuations derived from them, were discussed separately in contrasting the peculiar nature of liquid H2O against a typical van der Waals liquid, benzene. The composition dependence of these fluctuations was examined in aqueous solutions of typical hydrophobic solutes, 2-butoxyethanol, 2-butanone and tert-butanol. It was concluded that the above solutes reduce the hydrogen bond probability in H2O up to the crossover point of mixing scheme, x(i)(c).