Question

What is iodine solution changing from amber-yellow to blue-black an indication of?

a.the presence of reducing sugars or monosaccharides
b.the presence of proteins or peptide bonds
c.the presence of lipids or fats
d.the presence of starches or complex carbohydrates submit for grading save and finish later?

Answer 1

The answer is D. Iodine is used to test for starches and, in the presence of a starch, it will turn a dark blue-black color.

Answer 2

Iodine solution is prepared by dissolving iodine in a solution of potassium iodide. This iodine reagent is amber-yellow colored. When this iodine solution is added to starch solution which is a polysaccharide, the yellow colored reagent changes to blue-block color. This color change is due to the formation of a charge transfer complex between starch and the triioidide present in iodine solution. So, the correct answer is d. the presence of starches or complex carbohydrates