Question

Which compound gives red colour in Fehling’s solution?

Answer 1

Hint : The Fehling’s test is a standard method for estimating and distinguishing between reducing and non-reducing sugars. This test, developed by German scientist H.C Von Fehling, is frequently used to discriminate between water-soluble carbohydrate functional groups and ketones.

Complete Step By Step Answer:
Objectives of Fehling’s Test:
To detect the presence of carbohydrates in a solution.
To distinguish between sugar reducers and non reducers.
In Fehling's test, glucose produces a red colour.
In warm water beakers, Fehling's reagent, a blue-colored basic bistartratocuprate(II) complex solution, is combined with three different aqueous sugar solutions.
A brick-red precipitate forms when glucose and fructose are together.
There is no response in the test tube containing sucrose solution.
Uses of Fehling’s solution:
It's utilized to figure out whether a carbonyl group belongs to the aldehyde or ketone family. Aldehydes are oxidized and have a beneficial outcome. Aside from alpha-hydroxy-ketones, ketones do not react.
Fehling's test can also be used as a generic monosaccharide test, yielding positive results for aldose monosaccharides and ketose monosaccharides.
It's also used in medicine to check for the presence of glucose in the urine. It is useful to know whether or not the person is diabetic.

Note :
The Fehling test is based on the fact that acid is formed when the aldehyde group of sugar is oxidized by complexed copper ions. The redox reaction is then shown by the precipitation of red copper (I) oxide. Sugars can exist as a ring or as an open chain molecule in aqueous solution.