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Homework Help: Electrochemical cells

  1. Nov 21, 2011 #1
    1. The problem statement, all variables and given/known data
    Based on the following chart, what ions would you use to construct an electrochemical cell with potential closest to 2.00 V?

    [PLAIN]http://img546.imageshack.us/img546/5568/electrochemicalcellchar.png [Broken]

    2. Relevant equations
    I know that I am supposed to add the voltages of the 2 reactions but I am not sure how the signs would go. We are not using a textbook for this class so I have nothing to reference.


    3. The attempt at a solution
    I'd use the following reactions and voltages
    Fe3+ -> Fe2+ (-0.771 gaining electron)
    Na (s) -> Na+ (+2.71 losing electron)

    so the cell voltage would be 1.94V. Is this correct?
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Nov 21, 2011 #2

    Borek

    User Avatar

    Staff: Mentor

    Think about simple math - what is the distance between -2.7 and +0.7 points?
     
  4. Nov 21, 2011 #3
    Thank you, that was very helpful!
     
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