Which term describes the energy required to change a liquid to a gas at its boiling point?

• A. Heat
• B. Latent Heat of Fusion
• C. Latent Heat of Vaporization
• D. Light

Answer: (C)

When a liquid reaches its boiling point, energy put into it goes into breaking intermolecular forces so molecules can escape into the vapor phase. This specific energy is called latent heat of vaporization, and it is released or absorbed during a phase change without changing the temperature. The temperature stays constant at the boiling point while the liquid is converting to gas, which is why this energy is described as latent (hidden) heat.

This is distinct from latent heat of fusion, which is the energy required to melt a solid into a liquid at its melting point, and from heat in general, which is any energy transfer that raises temperature. Light is not the energy needed for the phase change itself in this context.