Specific heat capacity and latent heat

The change in thermal energy associated with a temperature change in a system is given by \(\text{energy}=\text{mass}\times\text{specific heat capacity}\times\text{temperature change}\) or \(\Delta E=mc\Delta\theta\).
When heating a substance as it is changing state, its internal energy will increase but its temperature will not change. This can be noticed on a heating or cooling graph for the substance.
The specific latent heat of a substance is the energy required to change the state of one kilogram of the substance without changing its temperature.
- The specific latent heat of fusion is the specific latent heat for changing the substance from solid to liquid.
- The specific latent heat of vaporisation is the specific latent heat for changing the substance from liquid to gas.
The energy required to change state is given by \(\text{energy}=\text{mass}\times\text{specific latent heat}\). This can be written as \(E=mL\) where:
- \(E\) is the energy required to change state in J
- \(m\) is the mass of the substance in kg
- \(L\) is its specific latent heat in J/kg

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