Changes of state occur at particular phase transition temperatures. The heat associated with the phase transition is given by:

freezing or melting: Q = mL_f   L_f is the latent heat of fusion

boiling or condensing: Q = mL_v   L_v is the latent heat of vaporization

For water:   L_v = 2256 kJ/kg;   L_f = 333 kJ/kg;  c = 4.186 kJ/(kg °C)