Question

While using iodine in the laboratory, some drops of iodine fell on Asha’s socks and some fell on her teacher’s saree. The drops of iodine on the saree turned blue black while their colour did not change on the socks. What can be the possible reason?

Answer 1

the saree was made up of cotton and as a result of this the starch which is present in the cotton resulted in the blue black colour

Explanation:

• starch reacts with iodine solution to form a complex. This complex is blue black in colour. But it is evident that the shocks are made up of of polymer and as a result of this there was no change in the colour suggesting that there was no presence of starch in the polymer.
• Iodine plays a very important role in the identification of the type of polysaccharide starch if present in a solution