Which term correctly describes a foam?

Which term correctly describes a foam?

• A. Foam
• B. Aerosol
• C. Sol
• D. Gel

Answer: (A)

Gas bubbles dispersed in a continuous phase of liquid or solid define a foam. This means the dispersed phase is gas, while the surrounding medium is either a liquid (as in shaving foam or beer foam) or a solid (as in a cellular solid). An aerosol, by contrast, is fine particles of liquid or solid dispersed in a gas, not gas bubbles in a liquid or solid. A sol is a solid dispersed in a liquid, and a gel is a liquid immobilized within a network. So the term that best describes the system shown is foam because it specifically names a gas-in-liquid or gas-in-solid colloidal structure.

Gas bubbles dispersed in a continuous phase of liquid or solid define a foam. This means the dispersed phase is gas, while the surrounding medium is either a liquid (as in shaving foam or beer foam) or a solid (as in a cellular solid). An aerosol, by contrast, is fine particles of liquid or solid dispersed in a gas, not gas bubbles in a liquid or solid. A sol is a solid dispersed in a liquid, and a gel is a liquid immobilized within a network. So the term that best describes the system shown is foam because it specifically names a gas-in-liquid or gas-in-solid colloidal structure.