What is the term for a phase change that occurs without a temperature change?

What is the term for a phase change that occurs without a temperature change?

• A. Latent Heat
• B. Sensible Heat
• C. Heat Transfer
• D. Calorimetry

Answer: (A)

Latent heat is the energy involved in a phase change that does not change the temperature. When a substance reaches its phase-transition temperature, adding or removing energy changes its phase (solid to liquid, liquid to gas, etc.) without changing its temperature. That energy goes into altering the internal structure—overcoming or forming intermolecular forces—rather than increasing molecular kinetic energy. The amount of energy per unit mass during these transitions is the latent heat (fusion for melting/freezing, vaporization for boiling/condensation), described by Q = mL. Once the phase change is complete, further energy would then change the temperature again (sensible heat). The other terms refer to different ideas: sensible heat changes temperature; heat transfer is the process of energy movement; calorimetry is the measurement of heat transfer.

Latent heat is the energy involved in a phase change that does not change the temperature. When a substance reaches its phase-transition temperature, adding or removing energy changes its phase (solid to liquid, liquid to gas, etc.) without changing its temperature. That energy goes into altering the internal structure—overcoming or forming intermolecular forces—rather than increasing molecular kinetic energy. The amount of energy per unit mass during these transitions is the latent heat (fusion for melting/freezing, vaporization for boiling/condensation), described by Q = mL. Once the phase change is complete, further energy would then change the temperature again (sensible heat). The other terms refer to different ideas: sensible heat changes temperature; heat transfer is the process of energy movement; calorimetry is the measurement of heat transfer.