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

Answer: (A)

Enthalpy of fusion + enthalpy of vapourisation

Answer 2

: Solid $\overset{\quad Sub\lim ation\quad}{\rightarrow}$Vapour

This process occurs in two steps,

Step 1 : Solid $\overset{\quad Fusion\quad}{\rightarrow}$ Liquid

Step 2 : Liquid $\overset{\quad Vaporisation\quad}{\rightarrow}$ Vapour

Thus, Enthalpy of sublimation = Enthalpy of fusion + Enthalpy of vaporisation.