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Questions on electrochemical cells using Zn, Cu

  1. Apr 18, 2007 #1
    The problem

    http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/animations/CuZncell.html

    After veiwing the animation found at the website above answer these questions:

    Is there an electron transfer between species?

    Which species is losing electrons

    Which species is gaining electrons?

    Write down the oxidation half reaction under the species that is undergoing oxidation.

    Write down the reduction half reaction under the species that is undergoing reduction.

    What is the Anode?

    What is the Cathode?

    Which direction is the spontaneous reaction? Explain your reasoning.

    Write the complete balanced equation for the reaction.


    2.The attempt at a solution

    Is there an electron transfer between species? Yes

    Which species is losing electrons? Zinc/Zn

    Which species is gaining electrons? Copper/Cu

    Write down the oxidation half reaction under the species that is undergoing oxidation. Zn-> Zn 2+

    Write down the reduction half reaction under the species that is undergoing reduction. Cu 2+ ->Cu

    What is the Anode? Zinc/Zn

    What is the Cathode? Copper/Cu

    Which direction is the spontaneous reaction? Explain your reasoning.

    The spontaneous reaction is occuring from the zinc to the copper because the zinc is losing electrons and the copper is gaining electrons.

    Write the complete balanced equation for the reaction.

    Zn 2+ + Cu --> Cu 2+ +Zn

    :surprised :surprised

    Please help me here!!

    I need someone to check my answers, I'm pretty sure about the first ones, but the last one about the balanced equation I think it wrong.


    Any help would be greatly appreciated.


    THANKS!!
     
  2. jcsd
  3. Apr 18, 2007 #2
    PLEASE please PLEASE HELP!!!
     
  4. Apr 18, 2007 #3

    chemisttree

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    If copper is the species being reduced, how can your reaction be correct?

    Zn 2+ + Cu --> Cu 2+ +Zn ??????
     
  5. Apr 24, 2007 #4
    Thats exactly why I need help ! !!
     
  6. Apr 24, 2007 #5

    chemisttree

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    You will notice that the metallic zinc electrode is being converted to Zn+2 and that the Cu+2 ions in solution are picking up electrons and depositing on the surface of the copper electrode. Write down these two processes one after the other:

    A+2 + 2e- ------> A
    B -------> B+2 + 2e-
    ______________________

    Add them together and see what you get...
     
  7. Apr 25, 2007 #6
    A+2 + B ---> B+2 + A

    we don't factor in the 2e- because they cancel each other out right?

    so it would be:

    Zn+2 +2e- ----> Zn
    Cu----> Cu+2 + 2e-
    ___________________
    Zn+2 + Cu----> Cu+2 + Zn


    Right?
     
  8. Apr 25, 2007 #7
    wait thats what I had before...

    oh god.

    would it be

    Cu+2 +Zn ----> Cu + Zn+2 ?
     
  9. Apr 25, 2007 #8

    chemisttree

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    That's correct. Now examine each of the metals in the equation. Which one is being oxidized and which is being reduced?
     
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