Question

Show what happens when $N{H_4}Cl$ is heated?

Answer 1

Hint : A chemical reaction in which the compound breaks down into two or more simple substances on heating is known as a decomposition reaction. Generally, decomposition reactions are endothermic in nature i.e., the reaction requires the input of energy in form of heat or light to form the products.

Complete Step By Step Answer:
The chemical formula of ammonium chloride is $N{H_4}Cl$ . The decomposition of sodium chloride depends at what temperature or to what extent it is heated. If $N{H_4}Cl$ is slightly heated then no reaction is observed but when the solid crystals of ammonium chloride are strongly heated (to about ${340^o}C$ ), then the decomposition reaction takes place and ammonia gas and hydrogen chloride gas are formed as the product. The reaction proceeds as follows:
$N{H_4}Cl\xrightarrow{\Delta }N{H_3} + HCl$
The gases formed are toxic gases with a pungent smell which are irritating and could be harmful if inhaled. As the $HCl$ gas is heavier than $N{H_3}$ gas, these gases can be separated by use of this reaction.
When ammonia gas and hydrogen chloride gas rise in the atmosphere, they recombine to form ammonium chloride that appears like smoke. Hence, upon heating of ammonium chloride, the system will form an equilibrium between $N{H_4}Cl$ , $N{H_3}$ and $HCl$ . Increasing the temperature of the system will lead to shift the equilibrium towards ammonia and hydrochloric acid.

Note :
It is important to note that although the decomposition of solid ammonium chloride directly converts into gaseous compounds, without any liquid intermediate formed. But it cannot be called a sublimation process, because in the reaction both physical and chemical changes occur simultaneously.