Question

State what you would observe when: Dilute hydrochloric acid is added to zinc sulphide.

Answer 1

• When dilute hydrochloric acid is added to zinc sulphide, a colourless gas with a foul smell like rotten egg is evolved i.e. ${\mathrm{H}}_2\mathrm{S}$ (Hydrogen sulphide gas).
• $\underset{\mathrm{Zinc}\mathrm{sulphide}}{\mathrm{ZnS}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Zinc}\mathrm{chloride}}{{\mathrm{ZnCl}}_2(\mathrm{s}})+\underset{\mathrm{Hydogen}\mathrm{sulphide}}{{\mathrm{H}}_2\mathrm{S}\uparrow }$
• Conclusion: Here we observe that a colourless gas ${\mathrm{H}}_2\mathrm{S}$is evolved along with the formation of zinc chloride.