Which process involves the merging of small droplets into larger droplets?

• A. Creaming
• B. Flocculation
• C. Coalescence
• D. Breaking

Answer: (C)

Coalescence is the process by which small droplets merge to form larger droplets. When droplets collide, if the stabilizing film around them is weakened or ruptured, the thin interfacial layer can break and the droplets fuse into a single, bigger droplet. This fusion reduces the total number of droplets and increases their size, which often changes the emulsion’s stability and rheology.

In contrast, creaming refers to droplets rising or settling due to density differences, not merging. Flocculation is droplets coming together into clusters without actually fusing into one larger droplet. Breaking describes the overall breakdown of an emulsion, which can involve coalescence but is more about loss of stability and phase separation rather than the deliberate fusion of droplets.