Heat capacities of true aqueous solutions of sodium decyl sulfate

The heat capacities of true aqueous solutions of sodium decyl sulfate (SDS) were determined from calorimetric measurements over a temperature range from 283 to 363 K. The apparent molar heat capacities Phi(Cp), partial molar heat capacities (C) over bar (p2), and relative partial molar heat capacities of the solute ((J) over bar (2)) and solvent ((J) over bar1) were calculated. It was found that Phi(Cp), (C) over bar (p2), and (J) over bar (2) linearly depend on the square root of the concentration. The temperature dependences of (J) over bar (1), (J) over bar (2), and (C) over bar (p2) at infinite dilution exhibit extremums. The results were explained by taking account of hydrophobic hydration and changes in the structure of the solvent.