Question

What do you observe when:

Dilute hydrochloric acid is added to sodium thiosulphate

Answer 1

The reaction of sodium thiosulphate ($N{a}_2{S}_2{O}_3$) with dilute hydrochloric acid ($HCl$) gives the following reaction:

$N{a}_2{S}_2{O}_3+2HCl\to 2NaCl+S{O}_2+S\downarrow +H_{2}O$

The reaction is not balanced as the total number of sodium is not balanced on the reactant and product sides. We write $2$ before $HCl$and before $NaCl$to make the reaction balanced.

$N{a}_2{S}_2{O}_3+2HCl\to 2NaCl+S{O}_2+S\downarrow +H_{2}O$