======Blue Bottle Experiment======


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**Alternative titles:** Shake-and-Change Redox Reaction
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====Summary====                   
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====Procedure====  
  - Add 300 mL of distilled water to a 500 mL Erlenmeyer flask.  
  - Dissolve 8 g of potassium hydroxide in the water.  
  - Add 10 g of glucose (dextrose) and swirl until dissolved.  
  - Add 6–8 drops of methylene blue indicator.  
  - Allow the solution to rest until it becomes colorless.  
  - Stopper the flask and shake gently once or twice. The solution should turn blue.  
  - Let the solution sit until the blue fades back to colorless.  
  - Repeat shaking to restore the blue color several times until the glucose is consumed.



====Links==== 
Blue Bottle Equilibrium - North Carolina School of Science and Mathematics: 
{{youtube>kGSPAkOgN3U?}}\\


📄🎞️ Blue bottle - MEL Science: [[https://melscience.com/US-en/chemistry/experiments/blue-bottle-us/?srsltid=AfmBOoooZ5BHx5Tl9ufHBrt_Ulu0Dz2_7W-3fQqtMvthwNbHBwml2Wdl]]\\

📄 BLUE BOTTLE EXPERIMENT  - QUT: [[https://cms.qut.edu.au/__data/assets/pdf_file/0014/24008/blue-bottle-experiment-teacher-worksheet.pdf]]\\

====Variations====
  * Warm the solution slightly to observe the effect of temperature on reaction rate.  
  * Use different concentrations of glucose to see how long the color cycling lasts.



====Safety Precautions====
  * Wear safety glasses to protect eyes.  
  * Potassium hydroxide is caustic and can cause severe burns—avoid skin and eye contact.  
  * Handle methylene blue with care, as it can stain skin and clothing.  
  * Dispose of chemicals according to institutional waste guidelines.




====Questions to Consider====
  * What role does methylene blue play in this experiment? (It acts as a catalyst that cycles between oxidized and reduced forms.)  
  * Why does the solution turn blue when shaken? (Shaking dissolves oxygen, which oxidizes the reduced indicator back to its blue form.)  
  * Why does the color fade when the solution is left to stand? (Glucose reduces methylene blue to its colorless form in the absence of oxygen.)  
  * What eventually stops the color changes? (All the glucose becomes oxidized, or oxygen is depleted from the system.)  
  * How is this experiment an example of a reversible reaction? (The methylene blue cycles between oxidized and reduced states multiple times.)