If iodine and water are mixed together and form a clear yellow solution and then cornstarch is added to iodine and form a dark brown color, what is the signifigance of the two different colors? Which one showed a positive presence of a sugar?
The significance of the two different colors observed when iodine is mixed with water and cornstarch can be explained by the chemical reactions that occur.
When iodine is mixed with water, it forms a clear yellow solution. This color change is due to the interaction between iodine molecules and water molecules, which leads to the formation of a complex known as the iodine-water complex. This complex gives the solution its characteristic yellow color.
When cornstarch, which is a type of complex carbohydrate (polysaccharide), is added to iodine, a different color change occurs. The iodine molecules react with the polysaccharide chains present in the cornstarch, forming a new complex known as the iodine-starch complex. This complex has a dark brown color.
The significance of the color change to dark brown in the presence of cornstarch is that it indicates the positive presence of a sugar. Starch, a polysaccharide made up of sugar units, is detected by the iodine solution, causing the formation of the iodine-starch complex and the color change. This reaction is often used as a simple test to identify the presence of starch in substances.
Therefore, the color change to dark brown after adding cornstarch to iodine solution indicates that there is a positive presence of a sugar, specifically starch, in the mixture.