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Blue Bottle Demonstration
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ward
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science
Recommended Grade Level(s):
Appropriate for: 6th Grade–10th Grade
Time Requirements:
Prep Time: 10 minutes
Activity Time: 30 minutes
Teaching Topics & Concepts:
• Redox reactions, developing a model
• Photochemical reactions (in alternate demo)
Materials:
• Sodium hydroxide, NaOH
• Glucose, C6H1206
• Methylene blue Indicator (1% in isopropyl alcohol)
• 500mL Erlenmeyer flask with rubber stopper
• Balance
Safety
• Read the SDS for all chemicals before using them.
• Sodium hydroxide is caustic. Handle with care
• Wear safety glasses, gloves and lab coat or apron.
!
Procedure:
1. Put 200 mL of water into Erlenmeyer flask
2. Add 5.0g of sodium hydroxide. Stir to dissolve
3. Add 5.0g of glucose. Stir to dissolve
4. Add 50 mL of water to the solution in the flask.
5. Add about 10 drops of 1% methylene blue indicator and gently swirl to mix
– Methylene Blue Indicator in its Oxidized form appears Blue (MB
oxidized )
– Methylene Blue Indicator in its Reduced form appears Colorless (MBreduced
)
6. Double-check the seal on your flask to confirm it's sealed, and shake the container
vigorously.
7. Leave flask undisturbed for approximately 60–90 seconds.
8. Shake the container again.
Expected Results:
Results may vary based on materials used, setup, procedure, and other factors, however, here are a few examples on what to expect:
• During step 5, the Methylene Blue solution will turn the solution blue briefly. The blue color will dissipate as you
gently swirl to mix. The solution will be colorless at the end of this step.
• During step 6, the solution will go from colorless to bright blue.
– Shaking introduces oxygen into the solution, oxidizing the colorless methylene blue, turning it blue.
• When the flask is allowed to settle during step 7, the solution becomes colorless again.
– The glucose reduces the Methylene Blue indicator, turning it colorless again.
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