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Exploding water?

  1. Aug 8, 2008 #1
    If you send electricity through water it breaks water molecules apart and creates oxygen and hydrogen gas. If electricity is still present wouldn't that cause the hydrogen and oxygen to react and cause an explosion or release of energy?

    I'm guessing this doesn't happen with electroysis of water to create hydrogen, but can someone please explain why this is?

    thanks
     
  2. jcsd
  3. Aug 8, 2008 #2

    russ_watters

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    Electricity doesn't automatically equal heat. There is no electric arc, just a current through the water.
     
  4. Aug 8, 2008 #3
    I still don't understand...what is electric arc? How does electricity not necessarilly mean heat? Can you explain further?

    Once you have the oxygen and hydrogen seperate, wouldn't you just need sufficient activation energy?
     
  5. Aug 9, 2008 #4

    Borek

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    Google electric arc, not that hard to find.

    Good point - but now think where does this activation energy come from. Just because there is a current flowing in the solution doesn't mean you are delivering enough energy for the activation!
     
  6. Aug 9, 2008 #5
    lets take water out of the equation.

    If you had a closed system filled with ONLY hydrogen and oxygen gas, and you tried apllying an electric current to the system, would a reaction occur?
     
  7. Aug 9, 2008 #6

    russ_watters

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    Gases at room temperature and standard pressure don't conduct electricity, so the only way to get electric current to flow through it is to arc it. An arc is lightning. That's where the heat comes from.

    Water conducts electricity - like a wire. Wires don't get hot because there isn't much resistance to the flow of electricity and therefore not much heat generated. Nor is there in water.
     
  8. Aug 9, 2008 #7

    Borek

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    I know what you mean, but it still hurts :wink: Similar heat effects, completely different mechanism.
     
  9. Aug 9, 2008 #8

    russ_watters

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    Fair enough. Yes, electricity in water water is through dissolved ions, in wires wires it's the 'sea of electrons'.
     
  10. Aug 10, 2008 #9

    If the cathode and anode were close enough together, and the voltage high enough that the electricity could arc through the gas between them, yes indeed, there would be a reaction. You'd have a high speed deflagration on your hands.
     
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