Question

Given,\[{\Delta _{sub}}H = {\Delta _{fusion}}H + {\Delta _{vap}}H.\]
If true enter 1 else 0.

Answer 1

Hint:Sublimation is the process of changing a solid to gas without going to the liquid phase. Fusion is the process of conversion of a solid to liquid phase. Vaporization is the process of conversion of a liquid to gas phase.

Complete step by step answer:
\[{\Delta _{sub}}H\] refers to enthalpy of sublimation, \[{\Delta _{fusion}}H\] refers to enthalpy of fusion and \[{\Delta _{vap}}H\] refers to enthalpy of vaporization.
The enthalpy of sublimation is defined as the change in the enthalpy during the transformation of one mole of a solid into its vapor state which occurs at a temperature below its melting point.
The enthalpy of fusion is defined as the change in enthalpy during the transformation of one mole of solid into the liquid state at its melting point.
The enthalpy of vaporization is the change in enthalpy during the transformation of one mole of liquid into the gaseous state at its boiling point.
Let us consider the sublimation of ice as an example. The sublimation of ice is shown as,
${H_2}O(s) \to {H_2}O(g)$
The above step can occur via two steps. Step \[1\] involves melting or fusion of solid to liquid and step \[2\] involves vaporization of liquid to gas.
$Step{\text{ }}1:{H_2}O(s) \to {H_2}O(l)$
\[Step{\text{ }}2:{H_2}O(l) \to {H_2}O(g)\]
Combining these two steps,
${H_2}O(s) + {H_2}O(l) \to {H_2}O(l) + {H_2}O(g)$
Cancelling \[{H_2}O\left( l \right)\]from both sides,
${H_2}O(s) \to {H_2}O(g)$ which gives the equation of sublimation
Thus \[step{\text{ }}1{\text{ }} + {\text{ }}step{\text{ }}2{\text{ }} = {\text{ }}sublimation\].
Hence \[{\Delta _{sub}}H = {\Delta _{fusion}}H + {\Delta _{vap}}H.\]
The statement is true so enter \[1\].

Note:
The enthalpy of sublimation is always greater than the enthalpy of vaporization. Both the process involves the change of the substance into a gaseous phase. The air fresheners used in toilets is an example of sublimation process where the solid vaporizes to generate pleasant smell.