Vitamin C as Reducing Agent
C6H8O6 + I2 → C6H6O6 + 2HI
Overview
Ascorbic acid (vitamin C) reduces iodine to iodide while being oxidized to dehydroascorbic acid. The enediol group on ascorbic acid is the active reducing center, losing two electrons. This reaction is the basis of the standard method for determining vitamin C content in foods.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Ascorbic Acid C₆H₈O₆ | 1 | (aq) |
| Reactant | Iodine I | 1 | (aq) |
Everyday Example
School science experiments often measure vitamin C in different juices by titrating with iodine solution until the starch indicator turns blue-black.
Industrial Importance
Vitamin C iodimetric assay is a standard pharmaceutical quality control method. Ascorbic acid's antioxidant action in food is based on its reducing properties.
Properties
- Type
- Redox
- Reversible
- No
- Energy
- Exothermic
- ΔH
- -58.0 kJ/mol
Related Reactions
Aqua Regia Dissolving Gold
Bleaching with Sodium Hypochlorite
Cerium(IV) Reduction by Iron(II)
Chlorine Oxidation of Bromide
Chromate-Dichromate Equilibrium
Contact Process SO₂ Oxidation
Copper Displaced by Iron
Copper Oxidation by Nitric Acid
Copper Patina Formation (Verdigris)
Copper Reduction of Silver Ion
Frequently Asked Questions
What is the equation for Vitamin C as Reducing Agent?
The balanced equation is: C₆H₈O₆ + I₂ → C₆H₆O₆ + 2HI.
What type of reaction is Vitamin C as Reducing Agent?
Vitamin C as Reducing Agent is a redox reaction.
Is Vitamin C as Reducing Agent exothermic or endothermic?
Vitamin C as Reducing Agent is exothermic (releases energy). The enthalpy change (ΔH) is -58.0 kJ/mol.