Question

Why is enthalpy of sublimation equal to the sum of enyhalpy of fusion and enthalpy of vaporisation ?

Answer 1

The 'enthalpy' of fusion is a latent heat, because during melting the heat energy needed to change the substance from solid to liquid at atmospheric pressure is latent heat of fusion, as the temperature remains constant during the process. ... The liquid phase has a higher internal energy than the solid phase.