JAMB Chemistry 2018 Paper

Concept:Laboratory preparation of nitrogen involves heating a mixture of ammonium chloride and a nitrite salt.Explanation:Sodium nitrite reacts with ammonium chloride to form ammonium nitrite and sodium chloride:$$\mathrm{NaNO}_2 + \mathrm{NH}_4\mathrm{Cl} \rightarrow \mathrm{NH}_4\mathrm{NO}_2 + \mathrm{NaCl}$$Ammonium nitrite is unstable and decomposes on heating to produce nitrogen gas:$$\mathrm{NH}_4\mathrm{NO}_2 \rightarrow \mathrm{N}_2 + 2\mathrm{H}_2\mathrm{O}$$Sodium dioxonitrate(III) is sodium nitrite, $\mathrm{NaNO}_2$.Answer:A. sodium dioxonitrate(III) and ammonium chloride