Question

Explain, why nitric acid makes wool yellow.

Answer 1

1. Nitric acid reacts with proteins in wool, which are made of complex organic compounds.
2. It attacks the protein, leading to the formation of a yellow substance called xanthoprotein.
3. This yellow compound causes wool to turn yellow when exposed to nitric acid.
4. The reaction is similar to the yellow stain nitric acid leaves on skin due to protein attack.
5. Thus, nitric acid’s action on the protein fibres in wool is responsible for the yellow colouration.