Which phase changes release energy?

Which phase changes release energy?

• A. Freezing, condensation, and deposition release energy.
• B. Melting, vaporization, and sublimation release energy.
• C. All phase changes release energy.
• D. None release energy.

Answer: (A)

Energy is released when a substance moves to a more ordered, lower-energy state. Freezing, condensation, and deposition all end up in solid or more ordered forms: liquid to solid, gas to liquid, and gas to solid. In each case, the particles lose energy and that energy leaves as heat to the surroundings, which is why these phase changes release energy. By contrast, melting, vaporization, and sublimation require adding energy to overcome intermolecular forces. So freezing, condensation, and deposition release energy.

Energy is released when a substance moves to a more ordered, lower-energy state. Freezing, condensation, and deposition all end up in solid or more ordered forms: liquid to solid, gas to liquid, and gas to solid. In each case, the particles lose energy and that energy leaves as heat to the surroundings, which is why these phase changes release energy. By contrast, melting, vaporization, and sublimation require adding energy to overcome intermolecular forces. So freezing, condensation, and deposition release energy.