Latent heat is defined as the energy required to...

Latent heat is defined as the energy required to...

• A. The energy required to raise the temperature of a substance.
• B. Energy released when a substance cools.
• C. The energy required to change phase without a temperature change.
• D. The energy needed to compress a gas.

Answer: (C)

Latent heat is the energy required for a substance to change its phase while the temperature stays the same. During a phase change, the added heat goes into breaking or forming intermolecular bonds rather than increasing the molecules’ kinetic energy, so the temperature does not rise or fall until the transition is complete. For example, ice at 0°C absorbs latent heat to melt into liquid water while the temperature remains 0°C, and liquid water at 100°C absorbs latent heat to become steam while the temperature stays at 100°C. If you’re simply raising a substance’s temperature, that’s sensible heat, which changes temperature rather than causing a phase change. Compressing a gas involves work and pressure-temperature changes, not latent heat.

Latent heat is the energy required for a substance to change its phase while the temperature stays the same. During a phase change, the added heat goes into breaking or forming intermolecular bonds rather than increasing the molecules’ kinetic energy, so the temperature does not rise or fall until the transition is complete. For example, ice at 0°C absorbs latent heat to melt into liquid water while the temperature remains 0°C, and liquid water at 100°C absorbs latent heat to become steam while the temperature stays at 100°C. If you’re simply raising a substance’s temperature, that’s sensible heat, which changes temperature rather than causing a phase change. Compressing a gas involves work and pressure-temperature changes, not latent heat.