“Ascorbic acid: a strong antioxidant” experiment
How vitamin C prevents oxidation
Did you think that ascorbic acid was just a tasty vitamin? It’s also a powerful antioxidant and reagent which can be used for impressive experiments! In this experiment you will learn about the main properties of ascorbic acid, and find out why it is so important for health.
Reagents and equipment:
- 3% hydrogen peroxide solution;
- 10% iron(II) sulfate solution;
- 10% ammonium thiocyanate solution;
- 1% ascorbic acid solution;
- lemon juice;
Into three beakers, pour an iron(II) sulfate solution. Add lemon juice to the first beaker, leave the second unchanged, and to the third, add a solution of ascorbic acid. Now pour the solutions of ammonium thiocyanate and hydrogen peroxide into each beaker. Observe the color change to red in the second beaker.
Antioxidants are substance which block oxidation reactions in the body. One of these substances is ascorbic acid. It is contained in many fruit and vegetables, for example in citrus fruit and red bell pepper.
In the first and third beaker, ascorbic acid blocks the oxidation of iron(II) to iron(III), i.e. it absorbs the oxygen radicals which form in the breakdown of hydrogen peroxide. There is no ascorbic acid in the second beaker, and we observe the red bond of iron (III) thyocyanate form
Fe²⁺ + 2H₂O₂ + 3CNS⁻ → Fe(CNS)₃ + 2H₂O + O₂