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Homework Help: Galvanic cell problem?

  1. Mar 16, 2014 #1
    Hey guys! I'm not sure if I solved this correctly. If you could please take a look at my answers I'd really appreciate it. Thank you in advance!

    (I tried using the super subscript option but I started to confuse myself because of all the coding so I just stuck with the up arrow (^) I hope you guys don't mind too much) Thanks again

    1. The problem statement, all variables and given/known data
    The following figure shows a diagram of an Al/Fe galvanic cell. Use the diagram to
    answer the questions that follow it.


    a) Predict the anode, cathode, and overall cell reactions that occur as this cell operates.
    b) Predict the overall cell potential.
    c) Describe the direction of ion and electron flow in the diagram.

    3. The attempt at a solution

    • Fe = Cathode
    • Al = Anode
    • Al(s) => Al^3+(aq) + 3e^- Fe^2+(aq) + 2e^- => Fe(s)
    2(Al => Al^3+ + 3e^-
    3(Fe^2+ + 2e^- => Fe)
    =2Al + 3Fe^2+ + 6e^- => 2Al^3+ + 6e^- + 3Fe
    =2Al + 3Fe^2+ => 2Al^3+ + 3Fe

    Al(s) => Al^3+(aq) + 3e^- E=1.66
    Fe^2+(aq) + 2e^- => Fe(s) E=-0.41
    Overall E= 1.25

    c) In an operating galvanic cell, electrons flow through the conducting wire, while ions flow through the solution and salt bridge.
  2. jcsd
  3. Mar 17, 2014 #2
    I couldn't see the picture, but I guess this is right

    What is the 6e- for?
    The reaction goes like this: 2Al => 2Al3+ + 6e-
    then 3Fe2+ + 6e- => 3Fe

    Umm..... you forgot to mention the direction of the flow of the electrons and ions. :biggrin:
    The electrons flow from the cathode(+) to the anode(-). The positive salt ions go to the anode(-) and the negative to the cathode(+)
  4. Mar 18, 2014 #3
    You sure? Seems they'd be going "uphill" so to speak.
  5. Mar 19, 2014 #4
    Really? Don't the electrons come from the anode? (I mean... oops sorry:redface:)
  6. Mar 19, 2014 #5
    Yep that's right! thanks a lot!:biggrin:
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