Conductance behaviour and thermodynamics of dissociation and micellization of calcium palmitate and stearate

Abstract

The critical micellar concentration of calcium soaps in a mixture of chloroform and propylene glycol of varying compositions has been determined at different temperatures by conductance measurements. The values of the limiting molar conductance and dissociation constant have been evaluated using Ostwald's dilution formula and DebyeHuckel's theory of weak electrolytes. The results show that these soaps behave as weak electrolytes in dilute solutions below the CMC and the CMC increases with increase in temperature. The various thermodynamic parameters have been evaluated for both dissociation and micellization processes. The results show that the association process is dominant over the dissociation process. The dissociation is found to be exothermic while the association process is endothermic in nature.