Interfacial Tension

Term normally used to characterize the force that seeks to minimize, to the greatest extent possible, the surface between two entities that cannot be merged—for example, oil and water. Interfacial tension between oil and water can be lessened and miscibility enhanced by adding a substance that is active at the interface—for example, soap or other amphiphilic substance, such as a lipid or a suitable protein. Surface tension is the interfacial tension between a surface and open space, usually air. This is the force that makes it possible to pour a meniscus on a glass of water.