- All phase changes…
- take place at a specific temperature and for a given pressure.
- take place without a change in temperature. (There is no temperature change during a phase change.)
- involve changes in internal potential energy.
- release or absorb latent heat.
- Endothermic phase changes absorb heat from the environment. (They are cooling processes.)
- Exothermic phase changes release heat to the environment. (They are warming processes.)
- The specific latent heat (L) of a material…
- is a measure of the heat energy (Q) per mass (m) released or absorbed during a phase change.
- is defined through the formula Q = mL.
- is often just called the "latent heat" of the material.
- uses the SI unit joule per kilogram [J/kg].
- There are three basic types of latent heat each associated with a different pair of phases.
|latent heat of…||fusion||vaporization||sublimation|
|endothermic phase changes||melting, liquefaction*||boiling, evaporation, vaporization||sublimation|
|exothermic phase changes||crystallization, freezing, fusion, solidification||condensation, liquefaction*||deposition|
|temperature||melting point, freezing point||boiling point, dew point||sublimation point, frost point|