What is "latent heat of vaporization"?

The concept of "latent heat of vaporization" refers specifically to the energy required to convert a unit mass of a liquid into vapor without a change in temperature. This phase change occurs at the boiling point of the liquid, where the energy absorbed is used to break the intermolecular bonds that hold the molecules in a liquid state, allowing them to enter the gaseous state.

This definition emphasizes that during the phase transition from liquid to vapor, the temperature remains constant, despite the continuous absorption of heat. The heat involved in this transition is crucial in various applications, such as in refrigeration cycles, where refrigerants must change states to absorb and release heat effectively.

The other choices, while related to phase changes and heat transfer, do not accurately describe the latent heat of vaporization. The first choice pertains to the heat of fusion—the energy required for a solid to change into a liquid. The second choice also describes the melting process rather than vaporization. The fourth choice refers to sensible heat transfer, which involves raising the temperature of water rather than a phase change. Understanding these distinctions is important for comprehending thermodynamic processes in power engineering.