Why does soap foam?
Show answer & explanation
Answer: Soap traps air in films
Soap traps air in films ✓ — Correct! Soap molecules reduce water's surface tension and form stretchy films. These films trap air, creating bubbles. Agitation introduces more air, making foam. More soap means more stable bubbles!
Chemical reaction with dirt — Wrong. Foam forms even in clean water with no dirt. It's the soap's ability to create stable air bubbles, not a cleaning reaction.
Water creates the foam — Wrong. Water alone doesn't foam—try shaking pure water. Soap's unique molecular structure is what enables foam formation.