Enthalpy of Sublimation
The enthalpy change when one mole of a solid converts directly into vapour.
Formula / equation
ΔH_sub = ΔH_fus + ΔH_vap
Unit
kJ/mol
In depth
Because enthalpy is a state function, sublimation enthalpy is simply the sum of the fusion and vaporisation values, whether or not the liquid phase is actually passed through. This identity is a textbook illustration of Hess's law in operation.
Examples in the real world
Iodine sublimes with ΔH_sub = 62.4 kJ/mol; solid CO₂ needs 25.2 kJ/mol.