Question

Assign appropriate reason for the following:

Bleaching of flowers by Cl₂ is permanent while by SO₂ is temporary.

Answer 1

1. Bleaching by Cl₂ is permanent because chlorine, in the presence of moisture, liberates nascent oxygen, which oxidizes the colored matter into a colorless product irreversibly.
2. Bleaching by SO₂ is temporary because it reduces the colored matter to a colorless form, which, on exposure to air, gets reoxidized back to the original colored form.
3. Thus, Cl₂ acts by oxidation, making bleaching permanent, while SO₂ acts by reduction, making bleaching temporary.