Question

why iodine solution is used in starch test

Answer 1

The iodine test is used to test for the presence of starch. Starch turns into an intense "blue-black" colour upon addition of aqueous solutions of the triiodide anion, due to the formation of an intermolecular charge-transfer complex. In the absence of starch, the brown colour of the aqueous solutionremains.

Answer 2

Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine. ... Iodine - KI Reagent: Iodine is not very soluble in water, therefore the iodine reagent is made by dissolving iodine in water in the presence of potassium iodide