Question

State one relevant observation for each of the following reaction.

Action of dilute Hydrochloric acid on Iron (II) sulphide.

Answer 1

• Dilute Hydrochloric acid ($\mathbf{HCl}$) when added to metal sulphide it forms their metal chloride and liberate Hydrogen sulphide (${\mathbf{H}}_{\mathbf{2}}\mathbf{S}$)gas with rotten egg smell.
• General reaction of metal sulphides with dilute hydrogen chloride is $$\begin{gathered} \mathrm{Metal}+\mathrm{Hydrochloric}\to \mathrm{Metal}+\mathrm{Hydrogen} \\ \mathrm{Sulphide}\mathrm{acid}\mathrm{chloride}\mathrm{sulphide} \end{gathered}$$
• Reaction between Iron(II) sulphide ($\mathbf{FeS}$) and Hydrochloric acid is $$\begin{gathered} \mathrm{FeS}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{FeCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right) \\ \mathrm{Iron}\left(\mathrm{II}\right)\mathrm{Hydrochloric}\mathrm{Iron}\left(\mathrm{II}\right)\mathrm{Hydrogen} \\ \mathrm{sulphide}\mathrm{acid}\mathrm{chloride}\mathrm{sulphide} \end{gathered}$$
• Therefore, a gas with rotten smell (${\mathrm{H}}_2\mathrm{S}$) is observed.