What is Fehling solution used to test for?

Fehling’s solution is a chemical reagent used to differentiate between water-soluble carbohydrate and ketone functional groups, and as a test for reducing sugars and non-reducing sugars, supplementary to the Tollens’ reagent test. The test was developed by German chemist Hermann von Fehling in 1849.

What is Fehling’s solution?

Fehling’s solution is a mixture of alkaline solution of copper(II) sulphate (CuSO4​) containing sodium potassium tartrate (Rochelle salt).

What is the principle of Fehling test?

The principle of the Fehling test is based on the fact that the aldehyde group of sugar is oxidised by complexed copper ions to form acid. The red copper (I) oxide then precipitates, which is an indicator for the redox reaction. Sugars can exist in aqueous solution as a ring shape or as an open chain molecule.

What is Fehling A and B?

Fehling A is a blue-colored aqueous solution of copper (II) sulfate (CuSO4). Fehling B is a colorless aqueous solution of potassium sodium tartrate (KNaC4H4O6·4H2O, also known as Rochelle salt) in an alkaline base like sodium hydroxide (NaOH).

Does formaldehyde give Fehling’s test?

Any aldehydic compound having an alpha hydrogen will show positive Fehling’s test. Formaldehyde and acetaldehyde both have alpha hydrogen. Thus, both compounds will show positive Fehling’s test.

What is the principle of Barfoed’s test?

Barfoed’s test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of copper(II) acetate to copper(I) oxide (Cu2O), which forms a brick-red precipitate.

Why does glucose give a positive Fehling’s test?

-The most important monosaccharides glucose, act as reducing agents in alkaline solution. It is in open chain aldehyde or ketone form in alkaline solution. It reacts with Fehling’s solution by reducing the copper(II) ions to copper(I) oxide and Thus, gives a positive result for Fehling’s test.

Why ketones are not oxidised?

Because ketones do not have hydrogen atom attached to their carbonyl, they are resistant to oxidation. Only very strong oxidizing agents such as potassium manganate(VII) (potassium permanganate) solution oxidize ketones.

How is the Fehling test used in the medical field?

Fehling’s test is also used as a general test for monosaccharides where a positive result is obtained for aldose monosaccharides and ketose monosaccharides. Apart from these, Fehling’s test is used in the medical field to determine the presence of glucose in urine. It helps to know whether the person is diabetic or not.

What kind of reaction does Fehling’s test show?

Reactions of Fehling’s Test. In Fehling’s solution the reaction between copper(II) ions and aldehyde is represented as; When tartrate is added: Common Uses of Fehling’s Test. Some of the common uses of Fehling’s test are; it is used to determine whether a carbonyl group is an aldehyde or a ketone.

What is the difference between Fehling’s A and B?

Initially, the solution exists in the form of two separate solutions which are labelled as Fehling’s A and Fehling’s B. Fehling’s A is a solution containing copper(II) sulphate, which is blue in colour.

How is glucose determined by Fehling’s reagent introduction?

Determination of Glucose by Titration with Fehling’s Reagent Introduction. Fehling’s test for reducing sugars has been used since the 1800’s to determine the amount of glucose and other reducing sugars (lactose in milk, for example).