Test for reducing sugars & carbon

What is a reducing sugar?

• A sugar that can donate electrons to another chemical

What is Benedict’s reagent?

• An alkaline solution of copper (II) sulfate

What happens when a reducing sugar is heated with Benedict’s reagent?

• When a reducing sugar is heated with Benedict’s reagent it forms an insoluble red precipitate of copper (I) oxide

Describe Benedict’s test

1. Add 2cm³ of food sample to be tested into a test tube. If the food is not in liquid form already, grind it up in water

2. Add an equal volume of Benedict’s reagent

3. Heat mixture in a gently boiling water bath for 5 mins

4. If a sugar is present, an insoluble red precipitate of copper (I) oxide should form

Explain why large molecules often contain carbon

• Carbon can very readily form bonds with other carbon atoms, permitting a large number of different types & sizes of molecules, all based on carbon, to be in chains of various lengths.