======Hydrogen and Oxygen Exploding Bubbles======


<WRAP right box>
**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
\\
**Categories:** {{$demo.categories}}
\\


**Alternative titles:** Electrolysis Bubbles Explosion
</WRAP>

====Summary====                   
{{$demo.summary}}



====Procedure====  
  - Set up a side-arm boiling tube with lead foil electrodes, a bung, and a delivery tube connected to a beaker of soapy water.  
  - Fill the tube with sulfuric acid solution until just below the side-arm. Seal with the bung.  
  - Place the delivery tube near (but not yet in) the soapy water.  
  - Connect electrodes to a 12 V DC power supply with an ammeter, and switch on (1–2 A current).  
  - Insert the delivery tube under the soapy water. Hydrogen forms at the cathode, oxygen at the anode, in a 2:1 volume ratio.  
  - Wait until air in the tubing has been displaced by the hydrogen–oxygen mixture.  
  - Use a spatula or teaspoon on a long stick to collect bubbles from the surface.  
  - Ignite the bubbles with a match on the end of a pole; they explode with a sharp crack.



====Links==== 
Exploding bubbles of hydrogen and oxygen - Royal Society of Chemistry: 
{{youtube>vcLHBS0yIVQ?}}\\

Hydrogen Bubbles - Exploding Bubbles - SpanglerScienceTV: 
{{youtube>zrg8XlHEDJ8?}}\\

📄 Exploding bubbles of hydrogen and oxygen - RSC: [[https://sciencequiz.net/ichemistry/wp-content/uploads/2019/02/Experiment-71-Exploding-bubbles-of-hydrogen-and-oxygen.pdf]]\\


====Variations====
  * Use a Hoffman voltameter to collect and show the 2:1 gas ratio separately before igniting.
  * Use graphite rods as the electrodes.
  * Experiment with different voltages and concentration of sulfuric acid. 
  * Compare loudness of bubbles filled with pure hydrogen, pure oxygen, and the hydrogen–oxygen mixture.


====Safety Precautions====
  * Wear safety goggles and ear protection.  
  * Perform only as a teacher demonstration — never scale up.  
  * Keep the Bunsen burner at least 1 m from the electrolysis setup.  
  * Lead foil is toxic — wash hands after handling and avoid ingestion.  
  * Sulfuric acid is corrosive — avoid contact with skin and eyes.  
  * Never ignite gas directly at the end of the tubing.  
  * Ensure the room is ventilated and that students keep a safe distance from the bubbles - it can be very loud.




====Questions to Consider====
  * Why is twice as much hydrogen produced as oxygen? (Because water has formula H2O, so electrolysis gives a 2:1 volume ratio of H2:O2.)  
  * Why do the bubbles explode so violently compared with burning pure hydrogen? (Because the gases are mixed in the exact stoichiometric ratio, allowing all reactants to combust at once.)  
  * Why is sulfuric acid added to the water for electrolysis? (It increases conductivity by providing ions.)  
  * Why is this reaction considered both endothermic and exothermic? (Electrolysis requires energy to split water — endothermic; recombination releases energy explosively — exothermic.)  
  * How could hydrogen fuel be produced for large-scale energy use? (By water splitting, though efficient catalysts and energy sources are still being researched.)