Which term is the energy required to melt or freeze a substance?

Which term is the energy required to melt or freeze a substance?

• A. Transpiration
• B. Adhesion
• C. Umbra
• D. Latent heat of fusion

Answer: (D)

Latent heat of fusion is the energy needed to change a substance from solid to liquid (melting) or from liquid to solid (freezing) at the same temperature. When a solid reaches its melting point, energy must be added to break the forces that hold particles in a rigid lattice, allowing them to flow as a liquid. The temperature stays constant during this phase change, and the amount of energy absorbed per unit mass is the latent heat of fusion. If the substance freezes, energy is released as the particles rearrange into a solid, with the same magnitude as the fusion energy but opposite in sign. This concept is distinct from sensible heat, which changes temperature without changing the phase. Transpiration, adhesion, and umbra refer to plant water loss, attraction between unlike substances, and the dark part of a shadow, respectively.

Latent heat of fusion is the energy needed to change a substance from solid to liquid (melting) or from liquid to solid (freezing) at the same temperature. When a solid reaches its melting point, energy must be added to break the forces that hold particles in a rigid lattice, allowing them to flow as a liquid. The temperature stays constant during this phase change, and the amount of energy absorbed per unit mass is the latent heat of fusion. If the substance freezes, energy is released as the particles rearrange into a solid, with the same magnitude as the fusion energy but opposite in sign. This concept is distinct from sensible heat, which changes temperature without changing the phase. Transpiration, adhesion, and umbra refer to plant water loss, attraction between unlike substances, and the dark part of a shadow, respectively.