Benedict's Reagent is also used to test for Non-Reducing Sugars. It is composed of Copper Sulphate in Aqueous Alkali.
Testing:
- The sample must be in liquid form.
- Add 3cm cubed of sample into a test tube and add an equal volume of dilute HCl.
- Heat the solution for 5 minutes in a gently boiling water bath.
- Slowly add 3cm cubed of sodium hydrogen carbonate to the test tube to neutralise the HCl. (Test with pH paper to make sure it is alkaline).
- Add 3cm cubed of Benedict's Reagent to test tube and heat tube for 5 minutes in boiling water.
Positive:
The solution forms an insoluble orange/brick red precipitate of copper (II) oxide.
Negative:
The solution stays a deep blue colour.
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