Thermodynamics of the Hydrophobic Effect

A thermodynamic theory is developed describing the transfer process of nonpolar substances from water to their pure state and the micellization process. The basis of the theory is the consideration, experimentally supported, that to a first-order approximation the change in the standard molar entropy (ΔS°) can be consider proportional to the standard molar heat capacity (ΔC p o) with proportionality constant, r, independent of the temperature and the pressure. In general it is found that the value of the magnitude of r decreases with the size of the solute molecule until a limiting value. This level of approximation is sufficient to predict observations such as linear plots between TΔS° and ΔH°, reduced behavior for surfactants with the temperature, and an important part of accepted phenomenology in the literature about the hydrophobic effect.