Abstract
In order to make clear the behavior of surface active molecules at oil/water interfaces, the interfacial tension was measured as a function of temperature, pressure, and concentration and analyzed by the thermodynamic equations derived. By measuring the interfacial tension between oil and water, the entropy, volume, and energy of interface formation were found to have positive values which are attributed to the repulsive intermolecular interaction between oil and water. Measurements of the interfacial tension of the oil solutions of surface active substances against water led us to the conclusion that the adsorption of surface active molecules at oil/water interfaces is accompanied by decreases in entropy, volume, and energy. Further, the affinity of oil to water was observed to affect the adsorption behavior of surface active molecules.
