Latent heat is the energy absorbed or released by a substance during a phase change (such as melting, boiling, or freezing) without changing its temperature.
Key points:
- During a phase change, energy goes into breaking or forming intermolecular bonds, not increasing kinetic energy—so temperature remains constant.
- It’s called “latent” because this energy is hidden—not detected by a thermometer.
Types of latent heat:
- Latent heat of fusion – energy absorbed when a solid turns to a liquid (e.g., ice melting).
- Latent heat of vaporization – energy absorbed when a liquid becomes a gas (e.g., water boiling).
- Latent heat of condensation/freezing – energy released when gas condenses or liquid freezes.
Latent heat plays a crucial role in weather systems, refrigeration, and heating processes, where large amounts of energy can be transferred with no temperature change.