How do the results of the Benedict’s test indicate that hydrolysis of sucrose and starch occurred? Benedict’s solution contains copper, which can accept electrons from reducing sugar and consequently change color, and positive Benedict’s sugar test will produce an orange to brick-red color. Reducing sugar have either a free aldehyde functional group or a free ketone functional group as part of their molecule structures. Starches and other polysaccharides lack these functional groups. If Benedict’s test change color (positive reaction polysaccharides must be hydrolyzed). 2. How do the results of the Iodine test indicate that hydrolysis of starch occurred? Starch is a polysaccharide which is stored as a reservoir for energy. It provides energy like of other polysaccharides. The presence of starch or polysaccharides is tested with the help of Iodine’s test. Starch tums the solution into blue-black when aqueous solutions of triiodine is added to it. This happens because of the intermolecular charge transfer complex. The cu^2+ changes to Cu^+. Make a CONCLUSION
The Correct Answer and Explanation is :
Conclusion
The results of the Benedict’s and Iodine tests provide clear indications that hydrolysis of sucrose and starch occurred. The changes in color during these tests reflect the chemical transformations that take place when complex carbohydrates are broken down into simpler molecules.
Explanation
- Benedict’s Test and Hydrolysis of Sucrose:
Benedict’s test is used to detect reducing sugars, which include monosaccharides and disaccharides that contain a free aldehyde or ketone group capable of being oxidized. In the test, the copper ions (Cu²⁺) in the Benedict’s solution are reduced by the aldehyde or ketone group of reducing sugars, which changes the solution color from blue to orange, red, or brick-red, depending on the amount of reducing sugar present. In the case of sucrose, a disaccharide, it initially does not have a free aldehyde or ketone group and therefore cannot reduce Cu²⁺ to Cu⁺ on its own. However, when sucrose undergoes hydrolysis (a process in which water breaks the bonds between sugar molecules), it is broken down into its constituent monosaccharides—glucose and fructose. Both glucose and fructose are reducing sugars and can react with Benedict’s solution, producing a color change from blue to orange or brick-red. Thus, the color change in Benedict’s test indicates that hydrolysis of sucrose has occurred. - Iodine Test and Hydrolysis of Starch:
Starch, a polysaccharide, contains many glucose molecules linked together by glycosidic bonds. When iodine is added to a solution containing starch, it forms an inclusion complex with the helical structure of starch, turning the solution a blue-black color. This color change indicates the presence of starch. When starch is hydrolyzed, it breaks down into smaller sugar units such as maltose or glucose. These smaller molecules no longer form the characteristic blue-black complex with iodine. Therefore, if the iodine test does not result in a blue-black coloration after a suspected hydrolysis reaction, it suggests that starch has been broken down into its simpler components, confirming that hydrolysis has taken place.
In conclusion, the Benedict’s test and the Iodine test together provide evidence that hydrolysis has occurred: the Benedict’s test indicates that sucrose has been broken down into reducing sugars, and the Iodine test shows that starch has been hydrolyzed into smaller sugar units that no longer react with iodine.