Adaptation of the drop-weight method for the quantification of surface tension: A simplified apparatus for the CMC determination in the chemistry classroom

ADAPTATION OF THE DROP-WEIGHT METHOD FOR THE QUANTIFICATION OF SURFACE TENSION: A SIMPLIFIED APPARATUS FOR THE CIVIC DETERMINATION IN THE CHEMISTRY CLASSROOM. The discussion based on surfactant cleaning action is commonly used in chemistry classrooms for the comprehension of theoretical concepts related to surface tension and micelle formation. The experimental quantification of surface tension of aqueous solutions of surfactants provides the practical instruments for this discussion. The present paper describes a simplification on the common apparatus employed for the drop-weight method, making the determination of surface tension accessible to any chemistry lab. The surface tension of various liquids and the critical micelle concentration, CMC, of three commercial surfactants were measured with this modified method, and proved to be consistent with literature values.