How to Do the Blue Bottle Chemistry Demonstration

How to Perform the Indigo Carmine Color Change Reaction

1. Prepare a 750 ml aqueous solution with 15 g glucose (solution A) and a 250 ml aqueous solution with 7.5 g sodium hydroxide (solution B).
2. Warm solution A to body temperature (~98-100°F). Warming the solution is important.
3. Add a 'pinch' of indigo carmine, the disodium salt of indigo-5,5’-disulphonic acid, to solution A. You want a quantity sufficient to make solution A visibly blue.
4. Pour solution B into solution A. This will change the color from blue -> green. Over time, this color will change from green -> red/golden yellow.
5. Pour this solution into an empty beaker, from a height of ~60 cm. Vigorous pouring from a height is essential in order to dissolve dioxygen from the air into the solution. This should return the color to green.
6. Once again, the color will return to red/golden yellow. The demonstration may be repeated several times.

• How to Do the Blue Bottle Chemistry Demonstration - Introduction and Materials
• How to Do the Blue Bottle Chemistry Demonstration - Procedure
• How to Do the Blue Bottle Chemistry Demonstration - Chemical Reactions
• How to Do the Blue Bottle Chemistry Demonstration - Other Colors