Question

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

Answer 1

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.