Latent heat of Vaporization is associated with which phase change?

• A. Solid to liquid
• B. Vapor to solid
• C. Vapor to liquid
• D. Liquid to Vapor

Answer: (D)

Latent heat of vaporization is the energy required to transform a liquid into a gas at a given pressure. This phase change—liquid turning into vapor—requires energy to overcome intermolecular forces and separates the molecules, so the temperature stays the same during the process. The absorbed energy goes into changing the phase, not increasing kinetic energy. When vapor becomes liquid again, the energy is released in the form of latent heat of condensation. Other phase changes involve different latent heats (for example, solid to liquid is fusion), but the latent heat of vaporization specifically corresponds to liquid changing into vapor.