Specific heat capacity and latent heat

Internal energy is the total kinetic and potential energy of the particles in a system. Heating raises the internal energy, either raising the temperature or changing the state. The specific heat capacity, c, is the energy needed to raise the temperature of 1 kg of a substance by 1 °C: ΔE = m c Δθ. Water has a high value, about 4200 J/kg °C.

During a change of state the temperature stays constant even though energy is supplied, because the energy breaks bonds between particles instead of speeding them up. The specific latent heat, L, is the energy needed to change the state of 1 kg without changing temperature: E = m L. Latent heat of fusion is for melting; latent heat of vaporisation is for boiling, and it is much larger.