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Homework Help: Calculating ξ° value for a galvanic cell

  1. Nov 1, 2011 #1
    Calculate the ξ° value for the galvanic cell:
    IO3(aq) + Fe2+(aq) <--> Fe3+(aq) + I2(aq)

    So I found the half reactions to be:

    5Fe2+(aq) --> 5Fe3+(aq) + 5e- Reducing agent 0.77V
    6H+(aq) + 5Fe2+(aq) + 5e- --> I2(aq) + 3H2O Oxidizing agent

    The problem I have is that I can't find the standard reduction potential for the cation's half reaction. Do I just use the potential for I2(s) + 2e- --> 2I- or this something special that I'm missing?

  2. jcsd
  3. Nov 2, 2011 #2


    User Avatar

    Staff: Mentor

    ξ°? and not E0?

    IO3(aq)? and not IO3-?

    It can be difficult to not reduced iodine further to I- in the presence of Fe2+, but perhaps with right stoichiometry reaction will stop at I2.

    Why 5?

    This is completely off - please check if that's what you meant.

    Not surprising - reaction you wrote doesn't make sense.
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