Critical Micellization Concentration of Ionic Surfactants: Comparison of Theoretical and Experimental Results

Theoretically calculated critical micellization concentration (CMC) of an ionic surfactant and the corresponding experimental value (CMC0) are compared. The CMC values are calculated within the framework of the quasi-chemical model. The CMC0 values are determined by the extrapolation of two linear parts of a dependence of a solution property on surfactant overall concentration. These parts of the aforementioned dependences correspond to the premicellar and micellar regions. The difference between CMC and CMC0 is found to be negligible and comparable with the measurement error. Cases in which this difference must be taken into account when estimating the properties of micellar solutions are discussed. It is shown that the micellization constant Kc of surfactant molecules can be calculated from the data on CMC0.