Question

$N{H_4}N{O_3}$ on heating at $250^\circ - 260^\circ$ gives the gas :
A) ${N_2}O$
B) ${N_2}$
C) $N{O_2}$
D) $NO$

Answer 1

The salt is ammonium nitrate . It decomposes to nitrous oxide and water when heated. The reaction is followed by liberation of heat.Reactions in which heat is evolved are known as exothermic reactions.

Complete solution:
The given salt is ammonium nitrate $N{H_4}N{O_3}$ . It is a white crystal solid and is highly soluble in water. It is predominantly used in agriculture as a nitrogen fertilizer. It decomposes at higher temperatures to evolve nitrous oxide and water.
Let us see what happens when ammonium nitrate is heated.
When $N{H_4}N{O_3}$ is heated at high temperatures the following reaction takes place :
$N{H_4}N{O_3} \to {N_2}O + 2{H_2}O$
We can see that the formation of nitrous oxide and water takes place. Ammonium nitrate salt does not leave any residue on heating. The reaction takes place slowly . The reaction is highly exothermic in nature and liberates large amounts of heat. Sometimes , this heat can even prove fatal ,if not handled properly .
The gas evolved here is nitrous oxide with the chemical formula ${N_2}O$. This is highly poisonous in nature and it is also known as laughing gas. This gas functions as a mild sedative . When inhaled it provides a euphoric feeling .
Hence, the correct option is A .

Note: This reaction is actually used as a synthesis reaction for synthesizing one of the most prominent oxide of nitrogen i.e. nitrous oxide.we should remember all the oxides of nitrogen so that we do not get confused while solving such questions.