Question

State your observations when
Dilute hydrochloric acid is added to sodium thiosulphate

Answer 1

1. Sodium thiosulphate$\left({\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3\right)$ reacts with hydrochloric acid$\left(\mathrm{HCl}\right)$ to give a reaction mixture that gets more cloudy as yellow sulphur is formed.
2. ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_{3_{\left(\mathrm{aq}\right)}}+2{\mathrm{HCl}}_{\left(\mathrm{aq}\right)}\to 2{\mathrm{NaCl}}_{\left(\mathrm{aq}\right)}+{{\mathrm{SO}}_2}_{\left(\mathrm{g}\right)}+{\mathrm{S}}_{\left(\mathrm{s}\right)}+{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}$