• An explanation of this phenomenon is because of cohesive force between the molecules of each separate liquid exceeds adhesive force between two liquids. This is manifested as interfacial energy or tension at boundary between the liquids.
• Therefore, to prevent the coalescence and separation, emulsifying agents have been used.
• Types of emulsifying agents:
1. Surface active agent: adsorbed at oil/water interface to form monomolecular film to reduce the interfacial tension
2. Hydrophilic colloids: forming a multimolecular film around the dispersed droplet
3. Finely divided solid particles: they are adsorbed at the interface between two immiscible liquid phases to form particulate film