Definition
Latent heat
(T2.2.1) T2.2 · Latent Heat →Statement
Heat absorbed or released during a phase change at constant temperature, with L the latent heat per unit mass.
Symbols and units
| heat transferred | J | |
| latent heat per unit mass | J/kg | |
| mass undergoing the phase change | kg |
When it applies
A substance undergoing a phase change at constant temperature and pressure.
Derivation
Since temperature does not change during a phase transition, there is no ΔT term — all the heat goes into converting substance from one phase to the other:
Watch out for
Temperature stays constant throughout the phase change itself — a common error is assuming temperature keeps rising while, for instance, ice is still melting.