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Balance the following equation for a half reaction that occurs in acidic solution. Use e– as the symbol for an electron.

Mo^3+ -> MoO2^2+

Is the answer 2O+2Mo^3+ -> MOO2^2++3e^-?

  • Chemistry -

    No. O should be written O2. Mo doesn't balance. Charge on left and right don't balance. The following are the steps. I think I gave you a site last night to show you how to do this. There are easier ways to do this but I prefer the following steps.
    Mo^3+ ==> MoO2^2+
    1. Determine the oxidation state of the elements and add electrons to the appropriate side to balance the change Mo is changing; on the left is +3. On the right is +6, so we add 3e to the right.
    Mo^3+ ==> MoO2^2+ + 3e

    2. Count up the charges on the two sides and add H+ (in acid solution or OH in a basic solution) to balance the charge.
    +3 on the left; -1 on the right. Add H^+ to the right.
    Mo^3+ ==> MoO2^2+ + 3e + 4H^+

    3. Ad H2O to the other side to balance H.
    Mo^3+ + 2H2O ==> MoO2^2+ + 3e + 4H^+

    4. Check everything.
    a. atoms:
    1 Mo left and right
    2 O left and right.
    4 H left and right
    b. charge:
    +3 on the left; +2 +4 -3 = 3+ on right.
    c. change in oxidation state:
    Mo^3+ ==> Mo^6+ + 3e

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