Table of Contents
Fehling’s Test
The Fehling’s test is a diagnostic test used to detect the presence of reducing sugars in a sample. The test utilizes two solutions: a copper sulfate solution and a sodium hydroxide solution. The copper sulfate solution is a blue color and the sodium hydroxide solution is a yellow color. When a reducing sugar is present in a sample, it will react with the copper sulfate solution to produce a red color. The presence of a red color in the test solution indicates the presence of a reducing sugar.
Procedure of Fehling’s Test
The Fehling’s Test procedure is as follows:
- A Fehling’s solution prepared by dissolving copper sulfate (CuSO 4 ) and sodium hydroxide (NaOH) in water.
- A sugar solution prepared by dissolving sucrose (C 12 H 22 O 11 ) in water.
- A test tube filled with the Fehling’s solution.
- The test tube then filled with the sugar solution.
- Test tube then heated until the sugar solution boils.
- The test tube then allowed to cool.
- The presence of copper in the sugar solution then observed.
If copper is present in the sugar solution, it will form a blue precipitate.
Reaction Of The Fehling Test
The Fehling test is used to determine the presence of aldehydes and ketones. A solution of copper (II) sulfate and sodium hydroxide added to a test tube. The tube then heated. If aldehydes or ketones are present, they will react with the copper (II) sulfate and sodium hydroxide to form a red precipitate.
Application of Fehling’s Test or Fehling’s solution
- A test for the presence of reducing sugars, specifically glucose, in aqueous solutions.
- Solutions containing reducing sugars will turn a deep red-brown in the presence of copper(II) sulfate (CuSO4) and sodium potassium tartrate (Na2C4H4O6), which are the reagents in Fehling’s solution.
