Question

Enthalpy of sublimation of a substance is equal to
(a) enthalpy of fusion + enthalpy of vapourisation
(b) enthalpy of fusion
(c) enthalpy of vapourisation
(d) twice the enthalpy of vapourisation.​

Answer 1

Explanation:

(a) Enthalpy of sublimation of a substance is equal to enthalpy of fusion + enthalpy of vapourisation.

Sublimation is direct conversion of solid to vapour, i.e., solid → vapour

Writing in two steps, we have solid → liquid → vapour.

Solid → liquid requires enthalpy of fusion.

Liquid →vapour requires enthalpy of vapourisation