Latent heat effects are associated with which of the following?

• A. Only heating processes
• B. Phase changes without a temperature change
• C. Temperature changes without phase change
• D. All of the above

Answer: (B)

Latent heat is the energy involved when a substance changes from one phase to another at essentially constant temperature. During a phase change, such as ice melting or water boiling, energy goes into altering the molecular structure (breaking or forming intermolecular bonds) rather than raising the temperature. That’s why you can add heat and the temperature stays the same while the substance changes state. In contrast, heating that raises or lowers the temperature without a phase change involves sensible heat. So latent heat effects are tied to phase changes without a temperature change, with examples including melting, freezing, vaporization, and condensation.