Representation of redox reaction Oxidation and reduction reactions occur together.

When hydrogen sulfide (H₂S) reacts with chlorine (Cl₂), sulfur (S) and HCl are formed.

H₂S + Cl₂ S + 2HCl

In this reaction, the H₂S is changing into ‘S’ i.e, hydrogen is being removed from hydrogen sulfide. Removal of hydrogen from a substance is known as oxidation. Hence hydrogen sulfide is being oxidized to sulfur.

Further, chlorine (Cl₂) is changing to HCl i.e, addition of hydrogen. In other words Cl₂ is reduced to HCl. Since oxidation and reduction occur simultaneously, the above is an example of redox reaction.