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RedOx Electron Balancing question

Discussion in 'Pre-Pharmacy' started by todaparty, Dec 3, 2008.

  1. todaparty

    2+ Year Member

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    Hey all, sorry for the hmwk question but I just had a quick Q...its late so maybe I'm missing something....

    Balance the RedOx Rxn: As2O3 + NO3- ---> H3AsO4 + N2O3



    1/2 reactions:

    4e- + AS2O3 + 5H20 ---> 2H3AsO4 + 4H+

    and

    2NO3- + 3H+ ---> N2O3 + 3H2O + 1e-

    So here's my question: Can I multiply the 2nd 1/2 rxn by 4 and the top by 1? Cuz when I do that and cancel out, the Hydrogens don't balance out...:scared:


    (4e- + AS2O3 + 5H20 ---> 2H3AsO4 + 4H+) x 1
    (2NO3- + 3H+ ---> N2O3 + 3H2O + 1e-) x 4

    4e- + AS2O3 + 5H20 ---> 2H3AsO4 + 4H+
    8NO3- + 12H+ ----> 4N2O3 + 12H20 + 4e-

    cancel out

    8NO3- + AS2O3 + 8H+ ----> 4N2O3 + 2H3AsO4 + 7H20

    8 H on the left, 20 on the right??:idea::confused:
     
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  3. AdamSanders

    AdamSanders Pharmacy Student
    7+ Year Member

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    Your original second half-reaction (before multiplying by 4) doesn't have the H balanced.
     
  4. todaparty

    2+ Year Member

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    yeah thanks :cool:, I just got to school and re-wrote the problem and I caught it.

    I corrected it in case anyone cares.
     

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