======Electrolysis of Water======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Splitting Water with Electricity
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====Summary====                   
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====Procedure====  
  - Fill the electrolysis apparatus with dilute sodium sulfate or sulfuric acid solution , ensuring both compartments are filled completely, then close the stopcocks.  
  - Connect the apparatus to a direct current power supply set to about 10–12 volts.  
  - Allow electrolysis to occur, collecting hydrogen gas at the cathode and oxygen gas at the anode.  
  - Test the hydrogen by igniting it with a lit splint or bunsen burner.  
  - Test the oxygen by inserting a glowing splint into the collected gas; it will reignite or glow more brightly.  
  - Rinse the apparatus thoroughly after the demonstration to prevent corrosion of electrodes.  




====Links==== 
Science at Home - SE1 - EP1: Electrolysis of Water - The Sci Guys (a much simpler setup): 
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Electrolysis of Water - Scott Milam: 
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📄 Electrolysis of Water - University of Washington: [[https://chem.washington.edu/lecture-demos/electrolysis-water]]\\


====Variations====
  * Add phenolphthalein indicator to the solution to show hydroxide ion formation at the cathode (solution turns pink).  
  * Collect larger amounts of hydrogen and oxygen to combine in a test tube for a small “pop” explosion.



====Safety Precautions====
  * Safety goggles required.  
  * Keep hydrogen away from open flames until intentionally tested.  
  * Do not exceed 12 volts to avoid damaging equipment or blowing fuses.  
  * Handle glassware and test tubes carefully to avoid breakage.  
  * Rinse apparatus immediately after use to prevent electrode corrosion.




====Questions to Consider====
  * What are the products formed when water undergoes electrolysis? (Hydrogen and oxygen gases.)  
  * Why is sodium sulfate added to the water? (It increases conductivity by providing ions but does not take part in the reaction.)  
  * How can you identify oxygen gas in this experiment? (It relights a glowing splint.)  
  * Why does hydrogen make a “pop” sound when ignited? (Because hydrogen combusts rapidly with oxygen to form water.)  
  * How does this experiment demonstrate conservation of matter? (The atoms of hydrogen and oxygen in water are rearranged into new molecules without being lost.)