Question

Give a test to distinguish between following pairs of compounds.

Hydrogen chloride ($\mathbf{HCl}$) gas and Hydrogen sulfide (${\mathbf{H}}_{\mathbf{2}}\mathbf{S}$) gas.

Answer 1

• For distinguishing Hydrogen chloride and Hydrogen sulfide, the chemical Ammonia can be used.
• Hydrogen chloride, when tested with Ammonia thick white fumes of Ammonium chloride, are observed.
• The reaction happening is,
• $$\begin{gathered} 2\mathrm{HCl}\left(\mathrm{g}\right)+{\mathrm{NH}}_3\left(\mathrm{g}\right)\to {\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{s}\right) \\ \mathrm{Hydrogen}\mathrm{Ammonia}\mathrm{Ammonium} \\ \mathrm{chloride}\mathrm{chloride} \end{gathered}$$
• While for Hydrogen sulfide (${\mathbf{H}}_{\mathbf{2}}\mathbf{S}$) no such white fumes are observed.
• In this way we can distinguish them.