Question

Which color is given by cellulose when treated with iodine solution? Explain.

Answer 1

Starch is tested to find the presence of starch in the plant parts. Starch is the reserve food material stored in plants mainly present in the leaves. When the starch comes in contact with iodine it will show a blue-black color. This blue-black color is the color of the starch iodide complex. When the iodine solution and potassium iodide solution are mixed in water, they will produce a brown color and after the addition of starch in that solution, the color will turn deep blue. The starch iodide complex absorbs visible light depending upon the energy intensity and thus giving a blue-black color.