Question

Why does hypo act as antichlor in bleaching of clothes?

Answer 1

1. Hypo is the short name for Sodium hyposulphite or Sodium thiosulphate(Na₂S₂O₃)
2. Antichlor is a dilute aqueous solution of Sodium thiosulphate which acts as a reducing agent and reduces unreacted Chlorine(Cl₂) in a redox reaction during bleaching of clothes.

Hypo act as an antichlor in the bleaching of clothes due to the following reason:-

Sodium thiosulphate(hypo) reduces the unreacted Chlorine produced by bleaching powder to form hydrochloric acid(HCl), Sodium Sulphate(Na₂SO₄) and atomic sulphur(S)

The Chemical equation of this reaction is,

${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3\left(\mathrm{aq}\right)+{\mathrm{Cl}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+\mathrm{HCl}\left(\mathrm{aq}\right)+\mathrm{S}$

Thus, Sodium thiosulphate or hypo acts as an antichlor during the bleaching of clothes.