Question
Benedict's reagent is added to a sugar solution. There is no change and a blue soluti is observed. After boiling in HCl and neutralizing with sodium hydrogen carbonate, more Benedict's reagent is added. An orange/red precipitate is formed. What can be concluded from these experiments? A non-reducing monosaccharide is present A reducing disaccharide is present There is no reducing sugar present A non-reducing disaccharide is present
Answer
4.2
(119 Votes)
Vina
Elite · Tutor for 8 years
Answer
A non-reducing disaccharide is present.
Explanation
## Step 1: Understand the initial observation. When Benedict's reagent is added to the sugar solution and no color change occurs (the solution remains blue), it indicates the absence of reducing sugars.## Step 2: Next, the sugar solution is boiled with HCl (hydrochloric acid). This step is used to hydrolyze any disaccharides or polysaccharides into monosaccharides. ## Step 3: After boiling, the solution is neutralized with sodium hydrogen carbonate. This step is necessary to neutralize the acid, as Benedict's reagent requires a neutral or slightly alkaline environment to function properly.## Step 4: Benedict's reagent is added again to the now neutralized solution. This time, an orange/red precipitate forms, indicating the presence of reducing sugars.## Step 5: Interpret the results. The initial absence of reducing sugars followed by the presence of reducing sugars after hydrolysis suggests that the original solution contained non-reducing sugars. The hydrolysis process converted these non-reducing sugars into reducing sugars.## Step 6: Identify the type of sugar. Since the hydrolysis of the solution led to the formation of reducing sugars, it indicates that the original sugar was a non-reducing disaccharide.#