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Selective Oxidation

  1. Nov 25, 2007 #1
    1. The standard reduction potential for the half-reaction

    Sn4+ + 2e- Sn2+
    is +0.15 V.
    Consider data from the table of standard reduction potentials for common half-reactions, in your text.

    For a galvanic cell under standard conditions, which of the following cathodic half reactions would produce, at the anode, a spontaneous oxidation of Sn to Sn2+ but not Sn2+ to Sn4+.

    Sn2+ + 2e- Sn
    Pb2+ + 2e- Pb
    2H2O + 2e- H2 + 2OH-
    PbSO4 + 2e- Pb + SO42-
    Fe2+ + 2e- Fe
    Fe3+ + 3e- Fe



    HOW DO I APPROACH THIS PROBLEM?
     
  2. jcsd
  3. Nov 25, 2007 #2
    any help >
     
  4. Nov 25, 2007 #3
    Well what are your thoughts on the problem. Also it seems kind of obvious from your choices think about it..
     
  5. Nov 26, 2007 #4
    Im not really sure how to approach this , i gues i have to look at standard potentials but im not sure what the question is asking me.
     
  6. Nov 26, 2007 #5
    Ok im confused this is wat i did
    Sn4+ + 2e- Sn2+
    is +0.15 V.

    For a galvanic cell under standard conditions, which of the following cathodic half reactions would produce, at the anode, a spontaneous oxidation of Sn to Sn2+ but not Sn2+ to Sn4+.
    Sn2+(aq) + 2e− → Sn(s) −0.13

    Sn2+ + 2e- Sn -0.13 V
    No not spontaeous this is at equilibirum?

    Pb2+ + 2e- Pb 0.13 V
    Yes because it is spontaneous and the Sn2+ to Sn4+ will occur at the cathode

    2H2O + 2e- H2 + 2OH- -0.828 V
    No because this will occur at anode since more negative

    PbSO4 + 2e- Pb + SO42- -0.359 V
    No because this will occur at anode since more negative

    Fe2+ + 2e- Fe −0.44 V
    No becuase this will occur at anode since more negative

    Fe3+ + 3e- Fe -0.04 V
    Yes the Sn will be oxidized to Sn2+ since it has lower potential -.13 and it is spontaneous and also the Sn2+ to Sn4+ will not happen at anode since it is much more postive.


    I ONLY HAVE 1 MORE TRY TO GET IT RIGHT ON MY ASSIGNMENT ONLINE PLZ HELPPPPPPPPPPPPPPP
     
    Last edited: Nov 26, 2007
  7. Nov 26, 2007 #6
    I think these are right but I dont want to submit them before making sure with someone smart at this forum since i only have one chance left.... lol :)

    please anyone check!
     
  8. Nov 28, 2007 #7
    I got it
     
    Last edited: Nov 28, 2007
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