Vitamin C - a Potent Antioxidant

Demonstration Experiment on Video

Vitamin C - a Potent Antioxidant

Objective: Reducing Ability of Ascorbic acid

Peter Keusch

German version

Supermarket products:

Vitamin C Tablets (Ingredients: Acidifying agent citric acid, sodium hydrogencarbonate, oligo fructose, Vitamin C, starch, sodium cyclamate , saccharin sodium, aroma, Riboflavin-5-Phosphate) Firm: SUNLIFE Produktions und Vertiebsgesellschaft mbH
Vitamin C Powder Firm: SUNLIFE Produktions und Vertiebsgesellscaft mbH

Chemicals:
Potassium permanganate solution (0.1 %)

Glass wares:

2 gas collecting cylinders h = 10 cm, d = 7 cm
glass stirring rod

Hazards and safety precautions:

Potassium permanganate is harmful if swallowed. Irritant. Readily absorbed through skin.

Safety glasses and adequate ventilation required.

Experimental procedure:

300 mL of aqueous potassium permanganate solution (0.1%) are placed into each of two gas collecting cylinders. A Vitamin C tablet is added is added to one of the two solutions. The other permanganate solution is mixed with a spatula full of Vitamin C powder. The solutions are stirred using a glass rod.

Results:

The permanganate solution mixed with Vitamin C powder is immediately decolorized. A color change from violet over brown to yellow can be observed in the second glass cylinder.

Videoclip (Download RealPlayer .rm file)

Discussion and background:

Ascorbic acid reduces permanganate ions to form Mn²⁺ ions. The color of the yellow solution is caused by riboflavin contained in Vitamin C tablets.

Vitamin C, or ascorbic acid is found in citrus fruits and green vegetables. It is made internally by almost all organisms, humans being one notable exception. As a potent antioxidant, Vitamin C eliminates free radicals (oxygen radical, hydroxyl radical, superoxide radical) in the human body and protects tissues from oxidative stress. Vitamin C catches the radicals and prevents their infiltration into the lipid system.
Vitamin C also promotes the absorption of iron, while preventing its oxidation. Fe²⁺ can be better absorbed in the human body (by more than 200%) than Fe³⁺. Due to the oxidation by air oxygen, iron is mostly present as poorly soluble Fe³⁺. On the one hand, Fe²⁺ is complexed by ascorbic acid and on the other hand ascorbic acid reduces Fe³⁺ to form Fe²⁺. So the absorption of iron in the human body is increased many times over.

Reference:
Microscale Projection Experiments Test for Vitamin C in Lemonade

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