Reaction with Dextrose and Ascorbic Acid: The Blue Bottle II
Demonstration: A mixture of dextrose, ascorbic acid, copper sulfate, sodium bicarbonate, and sodium chloride is treated with methylene blue or resazurin and allowed to settle. The indicators fade over the course of a few minutes. The solution is stoppered and shaken. The reaction between the oxygen and Dextrose causes the indicator to change. If allowed to rest, the color will again fade. This can be repeated several times. This new version is longer lasting and uses a protein coupled electron transfer mechanism in mild conditions and uses no hydroxide. It lasts much longer in solution than the original version and fades at the same rate.
C6H12O6(aq) + ascorbic acid C6H8O8 (aq) +2O2(g) ↔ C6H12O7(aq) +2H2O(l) + C6H8O9(aq)
Source: UW Card Catalog,
Shakhashiri, B.Z., “Chemical Demonstrations: A Handbook for Teachers of Chemistry”
Year: 1985 Vol: 2 Pages: 142- 146
Keywords: Acids and bases, Indicator, Redox, Reversible
Rating: 
Hazard: Low
- Breakage hazard
- Sharps hazard
- No use of toxic chemicals
- Standard lab conditions
- No use of reactive reagents
Effectiveness: Good
- Some connection from demo to course material
- Good contrast of system behavior
- Time to results is low
- Good reliability
- Repeatable phenomenon
- Mild effects are seen by audience
- Secondary effects are observed
Difficulty: Low
- Simple procedures
- Simple manipulation for most to perform
- No use of toxic chemicals
Safety Precautions:
- Eye protection required
- Gloves required
- Avoid exposure to droplets, liquids, or mists
- Handle flasks with care
Class: Matter and Mixtures, Reduction/Oxidation
Division: General, Organic Chemistry
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