Blue Bottle Reaction

Materials

Solution A: 8gm KOH in 300ml H₂O

Solution B: 10gm glucose

Solution C: 1% methylene blue solution

500 mL Wide Mouthed Bottle with Cap

Gloves and Goggles

Procedure

• Just before class starts, add glucose and 4 drops methylene blue solution to the KOH solution in the 500 mL bottle and mix until clear.
• Show the class the stoppered flask containing the solution.
• Give the flask a few shakes. The solution will turn blue.
• After a few seconds, solution becomes clear.
• This process can be repeated several times. The bottle may have to be unstoppered to introduce O₂.

Reactions

O₂ (g) --> O₂ (dissolved)

O₂ (dissolved) + methylene blue --> methylene blue 
                             (colorless)                  (blue)

glucose + OH^- --> glucoside

glucoside + methylene blue --> methylene blue + OH^-
                        (blue)                   (colorless)

Waste Management

The used solutions from this demonstration can be neutralized and then poured down the sink.