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Homework Help: Still that electrochemistry question

  1. Jul 7, 2007 #1
    my question is in three electrode system: working electrode, Pt counter electrode, and Ag/AgCl reference electrode.
    for example, Mn2+ + 2 H2O -MnO2 + 4 H+ + 2 e− ( −1.22 V), the deposition of Mno2 will be accomplished on postive potential. Cr3+ +3e- Cr ( −0.74 V), the depsotion of metallic Cr will be accomplished on negative potential.
    I Know for both the half-reactions, they are non-spontaneous and need external electric energy. My point is why the deposition of Mno2 is not done in negative potential range since E is equal to -1.22 V.

    I cannot put the arrow in the reaction. please ingore that.

    Thank you!
  2. jcsd
  3. Jul 9, 2007 #2


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    Are you asking what the difference is between plating out a conductive metal vs. a metallic oxide?
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