fehling's solution
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Definition
Noun: A chemical reagent used as a test for the presence of reducing sugars, such as glucose. It is an alkaline solution containing copper(II) sulfate, potassium sodium tartrate (Rochelle salt), and sodium hydroxide.
Usage
Fehling's solution is used specifically in analytical chemistry to detect aldehydes and reducing sugars. The test involves heating the solution with the sample. A positive result is indicated by a color change from deep blue to a brick-red precipitate of copper(I) oxide.
Examples
- In a laboratory experiment, the student added Fehling's solution to the liquid and heated it to test for the presence of glucose.
- A positive result with Fehling's solution confirmed that the patient's urine contained reducing sugars.
- The classic test for monosaccharides involves the use of Fehling's solution.
Advanced Usage
- Fehling's test: The procedure of using Fehling's solution to identify reducing sugars is commonly referred to as "Fehling's test."
- The Fehling's test is a standard qualitative analysis in organic chemistry.
Variants and Related Words
- Benedict's solution: A similar chemical reagent used for the same purpose, but it is a single solution and is considered more stable than Fehling's solution.
- Reducing sugar: A sugar that can act as a reducing agent, such as glucose or maltose, which gives a positive result with Fehling's solution.
- Copper(I) oxide (Cu₂O): The brick-red precipitate formed in a positive test result.
Synonyms
- Chemical reagent (specific to sugar detection)
- Test solution (in the context of sugar testing)
Notes
Fehling's solution is named after the German chemist Hermann von Fehling. It is typically prepared as two separate solutions (Fehling's A and Fehling's B) which are mixed just before use to ensure effectiveness.
Noun
- a liquid solution of copper sulfate and potassium tartrate and sodium hydroxide that is used to test for sugar in the urine; solution turns reddish when sugar is present