Sugars

Question 1

Reducing Sugar

Answer 1

• sugars that can donate an electron.
  - donates an electron to reduce copper (ll) ions in copper sulphate solution, which is blue
  - Cu (ll) ions are reduced to Cu (l) ions, in red copper (l) oxide

Question 2

Testing for the presence of sugars

Answer 2

• equal volume of benedict’s solution and the solution being tested are boiled.
• if a reducing sugar is present, e.g. glucose, the solution will change colour from blue to brick-red
• described as a qualitative test, as it doesn’t give the actual concentration of the reducing sugar

Question 3

Non-reducing sugars

Answer 3

Some disaccharide, e.g. sucrose cannot be detected by the benedict’s solution unless their broken down into their constituent monosaccharides.

Question 4

Testing for a non-reducing sugar

Answer 4

-Hydrochloric acid is added to the solution being tested.
- Alkali is added
- Benedict’s solution is added, and the solution is boiled
- If the solution turns red, a non-reducing sugar was initially present.