Question

A foul smell is produced when iron sulfate reacts with hydrochloric acid.

Answer 1

The reaction of FeS with acid:

• When iron sulphate $\left(\mathrm{FeS}\right)$ reacts with aqueous hydrochloric acid $\left(\mathrm{HCl}\right)$, a foul smell is produced due to the formation of hydrogen sulphide gas.
• It resembles the smell of rotten eggs.

$\mathrm{FeS}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{FeCl}}_2\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)$

Hence, a foul smell is produced due to the formation of hydrogen sulphide gas.