Influence of temperature on the micellization of sodium dodecylsulfate in water from speed of sound measurements

Speed of sound measurements for aqueous solutions of sodium dodecylsulfate (NaDS) have been carried out from 20 to 45°C at intervals of 5°C. The critical micellar concentrations (cmc) were determined and their change with temperature is discussed. A second change in the speed of sound has been found between 15 to 20mM for temperatures above 20°C. Values for G_m^o, H_m^o and S_m^o for the micellization process have been determined and compared with data previously obtained from other experimental properties. These results confirm that the micellization process of NaDS in water is mainly entropically driven.