A Simplified Method for the Determination of Critical Micelle Concentration

A simple and suitable method for the determination of critical micelle concentration of surfactants is described. The experiment was adapted from a traditional method and aims to familiarize undergraduate students with micellar solutions of amphiphilic molecules, versatile compounds exhibiting a wide range of applications. Surface tension is determined from the maximum bubble pressure required to form a bubble in a capillary tube just touching the liquid. The capillary is calibrated using liquids of known surface tension (at least 10 standard substances). Sodium dodecyl sulfate was selected to check the accuracy of the equipment.