Question

Answer the following question:

Dilute Hydrochloric acid is added to Sodium thiosulphate.

Answer 1

Reaction between Hydrochloric acid and Sodium thiosulphate:

• Hydrochloric acid reacts with thiosulphate to liberate sulphur dioxide gas.
• When dilute Hydrochloric acid $\left(\mathrm{HCl}\right)$ is reacted with Sodium thiosulphate$\left({\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3\right)$, it will give Sodium chloride $\left(\mathrm{NaCl}\right)$, Sulphur dioxide $\left({\mathrm{SO}}_2\right)$ gas, water $\left({\mathrm{H}}_2\mathrm{O}\right)$ and yellow residue of Sulphur$\left(\mathrm{S}\right)$ as a product.
• The solution becomes turbid due to the formation of sulphur.

Balanced chemical equation:

$\underset{\mathrm{Sodium}\mathrm{thiosulphate}}{{\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Sodium}\mathrm{chloride}}{2\mathrm{NaCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Sulphur}}{\mathrm{S}\left(\mathrm{s}\right)}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}+\underset{\mathrm{Sulphur}\mathrm{dioxide}\mathrm{gas}}{{\mathrm{SO}}_2\left(\mathrm{g}\right)}$