Question

A white solid A when heated with sodium hydroxide solution, gives a pungent gas B, which turns red litmus blue. The solid, when dissolved in dilute nitric acid and treated with silver nitrate gives a white precipitate of C which is soluble in an ammonia solution.
Identify A, B and C. Give equations to show the reactions involved.

Answer 1

Compounds A, B and C are:
A = Ammonium chloride
B = Ammonia gas
C = Silver chloride

The reactions involved are:

$$\begin{gathered} \underset{A}{{\mathrm{NH}}_4\mathrm{Cl}}+\mathrm{NaOH}\to \underset{B}{{\mathrm{NH}}_3}+\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O} \\ {\mathrm{NH}}_4\mathrm{Cl}+{\mathrm{AgNO}}_3\stackrel{\mathrm{dil}.{\mathrm{HNO}}_3}{\to }\underset{C}{\mathrm{AgCl}}+{\mathrm{NH}}_4{\mathrm{NO}}_3 \\ \mathrm{AgCl}+{\mathrm{NH}}_3\to \left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_4\right]\mathrm{Cl} \end{gathered}$$