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How do hydrogen and oxygen mix?

  1. Jan 9, 2016 #1
    So I'm curious, if you mix two parts hydrogen and one part oxygen in a bottle, how do they mix? I know that it wouldn't turn into water unless lit on fire. If the bottle was turned upside down and uncapped, would the oxygen fall out the bottom and hydrogen float to the top? Or are the two molecules stuck together so that both would end up falling out?
  2. jcsd
  3. Jan 9, 2016 #2


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    Ambient conditions? Google "entropy of mixing."
  4. Jan 9, 2016 #3
    They mix by diffusion. So, when you start out, they are essentially completely intermixed (provided you've waited long enough).
    First, what do you think would happen if you turned it upside down and it wasn't uncapped?
  5. Jan 9, 2016 #4
    I'm not sure. If it was lighter than air, it would float to the top. If it were heavier, it'd sink to the bottom?
  6. Jan 9, 2016 #5
    Why doesn't it do that when the bottle is right-side-up?
  7. Jan 9, 2016 #6
    Because... Gravity...?
  8. Jan 9, 2016 #7

    Vanadium 50

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    Not true - it takes very, very little energy to do this. Much less than can be provided by an ordinary spark due to static electricity. I've seen a balloon filled with a 2:1 mixture explode as soon as it touched the ceiling.

    When you think about Chestermiller's question - how does the gas know whether the bottle is right side up or upside down?
    Last edited: Jan 9, 2016
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