Question

Nitrogen gas can be obtained by heating:
A. Ammonium nitrate
B. Ammonium nitrite
C. Magnesium nitride
D. Ammonium chloride

Answer 1

Hint: Nitrogen gas is colourless and odourless. It is non-flammable in nature. We have to find out which among the given compounds produces nitrogen on thermal decomposition.

Complete step by step solution:
The chemical formula for ammonium nitrate is ${\text{N}}{{\text{H}}_{\text{4}}}{\text{N}}{{\text{O}}_{\text{3}}}$. When ammonium nitrate is heated it decomposes and produces nitrous oxide and water. The reaction when ammonium nitrate is heated is as follows:
${\text{N}}{{\text{H}}_{\text{4}}}{\text{N}}{{\text{O}}_{\text{3}}}\xrightarrow{{{\text{Heat}}}}{{\text{N}}_{\text{2}}}{\text{O}} + {\text{2}}{{\text{H}}_{\text{2}}}{\text{O}}$
Nitrogen gas cannot be obtained by heating ammonium nitrate. Thus, option (A) is not correct.
The chemical formula for ammonium nitrite is ${\text{N}}{{\text{H}}_{\text{4}}}{\text{N}}{{\text{O}}_{\text{2}}}$. When ammonium nitrite is heated it decomposes and produces nitrogen gas and water. The reaction when ammonium nitrite is heated is as follows:
${\text{N}}{{\text{H}}_{\text{4}}}{\text{N}}{{\text{O}}_{\text{2}}}\xrightarrow{{{\text{Heat}}}}{{\text{N}}_{\text{2}}} + {\text{2}}{{\text{H}}_{\text{2}}}{\text{O}}$
Nitrogen gas can be obtained by heating ammonium nitrite. Thus, option (B) is correct.
The chemical formula for magnesium nitride is ${\text{M}}{{\text{g}}_{\text{3}}}{{\text{N}}_{\text{2}}}$. When magnesium nitride is heated it decomposes and produces magnesium and nitrogen gas. The reaction when magnesium nitride is heated is as follows:
${\text{2M}}{{\text{g}}_3}{{\text{N}}_{\text{3}}}\xrightarrow{{{\text{Heat}}}}{\text{3}}{{\text{N}}_{\text{2}}} + 6{\text{Mg}}$
Nitrogen gas can be obtained by heating magnesium nitride. Thus, option (C) is correct.
The chemical formula for ammonium chloride is ${\text{N}}{{\text{H}}_{\text{4}}}{\text{Cl}}$. When ammonium chloride is heated it decomposes and produces ammonia and hydrochloric acid. The reaction when ammonium chloride is heated is as follows:
${\text{N}}{{\text{H}}_{\text{4}}}{\text{Cl}}\xrightarrow{{{\text{Heat}}}}{\text{N}}{{\text{H}}_3} + {\text{HCl}}$
Nitrogen gas cannot be obtained by heating ammonium chloride. Thus, option (D) is not correct.
Thus, nitrogen gas can be produced by heating ammonium nitrite and magnesium nitride.

Thus, the correct options are (B) and (C) ammonium nitrite and magnesium nitride.

Note:
Industrial preparation of nitrogen is done by heating a mixture of ammonium chloride and sodium nitrite. The heating of a mixture of ammonium chloride and sodium nitrite produces ammonium nitrite. Ammonium nitrite is very unstable and thus, it further decomposes to produce nitrogen and water.