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 su lfate (NaDS) in water were determined experimentally at 290 and 298 K. Thes e data were used to calculate the excess partial molar characteristics (ent ropy and enthalpy) of the solvent in terms of the Debye-Huckel theory of st rong electrolytes. In the region of high dilutions, these thermodynamic fun ctions 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.