Monosaccharides: Common Examples
- Sugars can be classified as reducing or non-reducing; this classification is dependent on their ability to donate electrons
- Reducing sugars can donate electrons (the carbonyl group becomes oxidised), the sugars become the reducing agent
- Thus reducing sugars can be detected using Benedict’s test as they reduce the soluble copper sulphate to insoluble brick-red copper oxide
- Examples of reducing sugars include: glucose, fructose and galactose
- Fructose and galactose have the same molecular formula as glucose however they have a different structural formula
- The different arrangement of atoms in these monosaccharides gives them slightly different properties
- Non-reducing sugars cannot donate electrons, therefore they cannot be oxidised
- To be detected non-reducing sugars must first be hydrolysed to break the disaccharide into its two monosaccharides before a Benedict’s test can be carried out
- Example: sucrose
The is a helpful mnemonic to remember the definitions of oxidation and reduction.
Examiner Tip
Become familiar with the OILRIG mnemonic to remember what happens to a molecule when electrons are lost from it (oxidation) or gained by it (reduction).
