Question

When nitrogen can be formed directly by decomposition of ammonium nitrate, why do we start with ammonia chloride in the laboratory?

Answer 1

Hint: We must have to remember that nitrogen is a chemical element and nitrogen compounds are nitric acid, ammonia, etc. are used as important compounds in industries. It is a nonmetallic element because of its high electronegativity and usual gaseous form and also nitrogen has a lack of solid form. At STP (standard temperature and pressure) two nitrogen atoms combine to form dinitrogen $(N_2^{})$ , an odorless gas.

Complete step by step answer:
We must have to know that in the laboratory method of preparation nitrogen is prepared by the reaction of ammonium chloride $(N{H_4}Cl)$ with sodium nitrate $(Na{O_2})$. This is heated and small amounts of water is added to this reaction. The product is ammonium nitrate $(N{H_4}N{O_3})$ and sodium chloride $(NaCl)$. This reaction is a double decomposition.
We can write the chemical equation for this chemical equation as,
$N{H_4}Cl + NaN{O_2} \to N{H_4}N{O_3} + NaCl$
The ammonium nitrate $(N{H_4}N{O_3})$ formed here decompose to form nitrogen and water vapor, see the below equation,
$N{H_4}N{O_3} \to {N_2} + 2{H_2}O$
Ammonium chloride is sublimed when heated so we add small quantities of water that prevent subliming.
If we start with ammonium nitrate $(N{H_4}N{O_3})$ initially, ammonium nitrate is heated, this reaction is very fast and this leads to explosive.
That’s why we start with ammonium chloride $(N{H_4}Cl)$ in the laboratory to prepare nitrogen.

Note:We must remember that the ammonium nitrate is not an explosive on its own but it is oxidized when oxygen is at surround and this creates a violent explosion and generates heat, nitrogen oxides also. When Ammonium nitrate is stable at STP. It is an important fertilizer. Ammonium nitrate is not a health hazardous substance.