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Conventional Cell Representation Alkaline Hydrogen-Oxygen Fuel Cell Help Watch

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    The question asked to write the 'Conventional Cell Representation Alkaline Hydrogen-Oxygen Fuel Cell'
    the mark scheme says this Pt|H2(g)|OH–(aq),H2O(l)||O2(g) |H2O(l),OH–(aq)|Pt it also says 'the h2o is not essential' so Pt|H2(g)|OH–(aq)||O2(g) |OH–(aq)|Pt
    My question is why is the OH- closest to the phase boundary as the most oxidized species should be there ie H2?
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    Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.

    You can also find the Exam Thread list for A-levels here and GCSE here. :dumbells:


    Just quoting in Puddles the Monkey so she can move the thread if needed
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    (Original post by Puddles the Monkey)
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    (Original post by Sniperdon227)
    The question asked to write the 'Conventional Cell Representation Alkaline Hydrogen-Oxygen Fuel Cell'
    the mark scheme says this Pt|H2(g)|OH–(aq),H2O(l)||O2(g) |H2O(l),OH–(aq)|Pt it also says 'the h2o is not essential' so Pt|H2(g)|OH–(aq)||O2(g) |OH–(aq)|Pt
    My question is why is the OH- closest to the phase boundary as the most oxidized species should be there ie H2?
    Can I see the question?
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    (Original post by SirRaza97)
    Can I see the question?
    http://filestore.aqa.org.uk/subjects...W-QP-JAN10.PDF

    http://filestore.aqa.org.uk/subjects...W-MS-JAN10.PDF

    Q3C Please
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    It's not the most oxidized species. It's the species formed in the solution which is in contact with the electrode which is next to the double lines. The question states that "commercial cells use porous platinum electrodes in contact with concentrated aqueous potassium hydroxide." So the species is OH- . Not H+ or H2. It also states that it's an alkaline cell not an acidic cell. If it was an acidic cell then it would be H+.
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    (Original post by SirRaza97)
    It's not the most oxidized species. It's the species formed in the solution which is in contact with the electrode which is next to the double lines. The question states that "commercial cells use porous platinum electrodes in contact with concentrated aqueous potassium hydroxide." So the species is OH- . Not H+ or H2. It also states that it's an alkaline cell not an acidic cell. If it was an acidic cell then it would be H+.
    cheers i learnt something
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    Hi Sniperdon227

    I remember this question and the mark scheme is awful! I have actually queried this question with the exam board and forced a response. The answer I would give to this question is this:

    Pt I H2 I H2O II O2 I OH- I Pt

    The reason for this is because from the equations given H2 is oxidised to H2O (zero to +1) and then in the next equation O2 is reduced to OH- (zero to -2).

    I hope that helps a bit, and as I have already said, the answer I have given would gain the marks, confirmed by AQA.

    Thanks

    Alex
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    (Original post by Sniperdon227)
    The question asked to write the 'Conventional Cell Representation Alkaline Hydrogen-Oxygen Fuel Cell'
    the mark scheme says this Pt|H2(g)|OH–(aq),H2O(l)||O2(g) |H2O(l),OH–(aq)|Pt it also says 'the h2o is not essential' so Pt|H2(g)|OH–(aq)||O2(g) |OH–(aq)|Pt
    My question is why is the OH- closest to the phase boundary as the most oxidized species should be there ie H2?
    Hiya! I moved this into the Chemistry forum as other Chemistry students might find it useful
 
 
 
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