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    Can anyone tell me whether or not we need to know about hydrogen-oxygen fuel cells with ACID and ALKALINE electrolytes? I understand (I think) what happens with an acid electrolyte, but not what happens with an alkaline electrolyte.

    My books seem to conflict each other, but maybe that's because I don't understand properly :confused: - if we do need to know both, can someone explain to me what happens at the anode and cathode in each (and include the half equations). Thanks!

    P.S this is what I understand so far of what happens in a fuel cell with an acid electrolyte:
    - At the anode the platinum catalyst splits the H2 into protons and electrons.
    - The H+ crosses the electrolyte membrane, forcing the e- to travel around the circuit to the cathode (creating an electric current).
    - At the cathode, O2 combines with the H+ from the anode and the e- from the circuit to make H2O.

    So, at the anode: H2 --> 2H+ + 2e-
    And at the cathode: 1/2O2 + 2H+ + 2e- --> H2O

    Can you explain to me what happens at which terminal when an alkaline electrolyte is used?
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    Can't anyone help me?
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    (Original post by Aliceo)
    Can anyone tell me whether or not we need to know about hydrogen-oxygen fuel cells with ACID and ALKALINE electrolytes? I understand (I think) what happens with an acid electrolyte, but not what happens with an alkaline electrolyte.

    My books seem to conflict each other, but maybe that's because I don't understand properly :confused: - if we do need to know both, can someone explain to me what happens at the anode and cathode in each (and include the half equations). Thanks!

    P.S this is what I understand so far of what happens in a fuel cell with an acid electrolyte:
    - At the anode the platinum catalyst splits the H2 into protons and electrons.
    - The H+ crosses the electrolyte membrane, forcing the e- to travel around the circuit to the cathode (creating an electric current).
    - At the cathode, O2 combines with the H+ from the anode and the e- from the circuit to make H2O.

    So, at the anode: H2 --> 2H+ + 2e-
    And at the cathode: 1/2O2 + 2H+ + 2e- --> H2O

    Can you explain to me what happens at which terminal when an alkaline electrolyte is used?
    I would take the time to learn it if I were you as the questions on this topic can be quite tricky, take a look on here for the equations: http://www.docbrown.info/page07/equilibria7d.htm
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    (Original post by clownfish)
    I would take the time to learn it if I were you as the questions on this topic can be quite tricky, take a look on here for the equations: http://www.docbrown.info/page07/equilibria7d.htm
    Okay, thanks, I've had a look at that now. So, do I need to be able to explain what happens in a fuel cell when an acid and an alkaline electrolyte is used? Or is it acceptable to just know one of them?
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    with an alkaline fuel cell:

    two half cell equations:

    2H20 + 2e --> H2 + 2OH- ( more negative so goes backwards)
    1/2 O2 + H20 +2e- -->2OH-

    This one is a little bit more difficult to understand as the electrolyte (OH-) is generated at the end even though it is used in the first equation.


    The more negative half equation is the first one, so it is oxidised. H2 reacts witht he alikaline elctrolyte to make water and two electrons. Just like with the acid fuel cell, the electrons travel through the wire, creating voltage. Once at the other side, the water now diffused across the membrane, and the electrons via the wire, both react with the added oxygen to make OH-. This OH- then can diffuse back across the membrane to react with more H2 and continue providing energy.
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    So at the anode:
    H2 + 2OH ---> 2H2O + 2e

    At the cathode:
    1/2 O2 + H2O +2e ---> 2OH

    Is this right?
    Thanks
 
 
 
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