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Effect of pressure on electrolysis of water

  1. Aug 6, 2007 #1
    I recently obtained a 45 watt solar panel, and have been thinking of setting up a hydrogen production experiment. I wonder if anyone has any experience with this that might be helpful? For example, it occurs to me that electrolysis in a closed chamber would have to produce an increase in pressure, and that this pressure must eventually slow the production of gasses. Where can I find the relevant formula? How can I calculate the equilibrium point?

    Thanks for any thoughts. I am aware that hydrogen is an explosive gas and that I need to take precautions. This is only a thought experiment so far, and the volume of my little set up is bound to be very small, so don't be overly concerned about my welfare.:smile:
  2. jcsd
  3. Aug 6, 2007 #2
    Just don't use a closed chamber. I think this is really a chemistry question.. try to use carbon electrodes, that kind of thing.
  4. Aug 8, 2007 #3


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    I know you probably already thought of this, but put your gas containers under the water upside-down above your electrodes, so when bubbles of gas form, they bubble up into the containers. That way you can use an open chamber without your gasses escaping. (Well, the ones in the experimant, anyway.)
  5. Aug 8, 2007 #4
    Thanks for the replies.

    Cesiumfrog, why do you suggest carbon electrodes? Is there an advantage to them over silver, platinum, or just plain copper?

    Lurch, my experiment will be table top of course, so your description is rather what I had in mind to start out. I am wondering what would happen if the containers were in deep ocean water....of course I have no such resources, but I thought it an interesting question. I have been looking for the necessary formulas to find out if it would be practical.

    The advantages to deep water production would be cold temperatures and high pressure, so the gas produced would already be cold and dense. Then when brought to the surface for use, the gas would warm up, and could be released as needed through valves.

    However it seems to me that the pressure at depth would result in a need for more amperage, which could negate part of the proposed advantage.

    I am imagining an experiment in which production of gas would be forced in a closed piston under constant pressure, varying amperage upward incrementally from zero to find the point at which electrolysis would no longer be suppressed. Repeated tests under different pressure conditions would establish the relationship between electrolysis and pressure.

    How can I find out if this has already been established? Just for fun.
  6. Aug 8, 2007 #5


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  7. May 21, 2009 #6
    Hi starkind,

    I'm so happy to see this question pop up, even if the last answer in this thread is quite old...

    It's a question I had also and if I remember well I read somewhere that this process is pressure insensitive, which makes no sense to me !

    But from what I understand it seems to be the case, and here is an application of this similar to your idea of high pressure ocean water electrolysis :


    Does it make sense ?
  8. May 21, 2009 #7
    don’t use copper electrodes they will corrode , you can take apart a 9v battery and get the carbon rods out of it and they work great . When i do it i add sodium hydroxide or hydrochloric acid to the water so the current flows nicely . And i was wondering if you do electrolysis deep in the ocean could when the gas is produced could it dissolve into the water at those pressures , And you could also do heat electrolysis heat water until it turns to steam and run it through the copper coil and then have a Bunsen burner on the coil and it would eventually break it into hydrogen and oxygen.
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