Question

In this lab, biology students were directed to use indicators as chemical detection tools, to analyze a variety of foods for the presence of carbohydrates, lipids or proteins. One group of students was given four unmarked containers of sugars: glucose, sucrose, fructose, and galactose. How could they use the standard lab tests to find the sucrose?

Answer 1

Answer:

Benedict's test which is meant to detect non-reducing sugar like sucrose from reducing sugars like glucose, fructose or galactose can be used to identify sucrose.

Explanation:

Glucose, fructose and galactose are reducing sugars so they can easily be identified against non-reducing like sucrose. A reducing sugar is a kind of sugar which has a free aldehyde or ketone group. Free aldehyde and ketone groups act as a reducing agent and they are capable of reducing other substances. In this situation, the reducing sugar reduces other substances and themselves get oxidized. In contrast to this, a non-reducing sugar can not act as a reducing agent because it has lack of a free aldehyde or ketone group.

Benedict's test is a test which is used to identify a non reducing sugar from reducing sugars. In this test, a reducing sugar (Glucose, fructose or galactose) is heated with Benedict's solution which leads to the change of color of solution to orange-red/ brick red. But no such color change will be detected if sucrose is heated with Benedict's solution.