The enthalpy of solution, the excess thermodynamic functions of the solvent, and the hydrophobic effect in aqueous solutions of sodium dodecyl sulfate

The solubility and the integral enthalpies of solution of sodium dodecyl sulfate (NaDS) in water were determined experimentally at 290 and 298 K. These data were used to calculate the excess partial molar characteristics (entropy and enthalpy) of the solvent in terms of the Debye-Huckel theory of strong electrolytes. In the region of high dilutions, these thermodynamic functions were negative at both temperatures. The negative excess entropies of the solvent were explained by a strong hydrophobic effect resulting from a combination of solvent restructuring processes.