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March 27, 2017

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I need help balancing this redox equation:

H2O2 + Ni+2 --> H2O + Ni+3 in basic solution.

Here's what I have so far:
Ni+2 --> Ni+3 + 1e-
H2O2 --> H2O

I can't seem to make the second half-reaction balance.

If you follow the rules for balancing basic redox solutions, this should work as follows:
H2O2 ==> H2O
First, add 2 to right to make two O atoms (so we are comparing the same number).
H2O2 ==> 2H2O.
Total charge on left O is -2. Total on right O is -4
Add 2 electrons to left to balance charge.
2e + H2O2 ==> 2H2O
Charge on left is -2. Charge on right is 0. Add OH^- to balance charge. So add 2 OH^- to right (this is a basic solution).
2e + H2O2==>2H2O + 2 OH^-
Then add water to other side to balance H atoms.
2e + 2H2O + H2O2==>2H2O + 2OH^-
Now cancel the 2H2O on each side to arrive at the final half equation.
2e + H2O2 ==> 2OH^- OR
we could have done it easier by simply going to OH^- initially.

H2O2 ==> 2 OH^-
Charge on left O is -2. right O is -4
Add 2e to left.
2e + H2O2 ==> 2 OH^-

Check my thinking and my work.

  • chem - ,

    I can do it two ways. I'm not sure which way is right though. Here is way 1.

    (If you don't make the oxygen into O2.)

    Also I think you just confusing yourself. You don't need to add any OH.

    This is how I would do it.

    Equation: H2O2 ==> H2O +O
    Charge: -1 ==> -2
    Solution: add +1e- to the left hand side so the charges equal.

    Therefore:

    H2O2 +1e- ==> H2O + O


    Way 2.


    Equation:2H2O2 ==> 2H2O +O2
    Charge: -2 0
    Solution: add 2 electrons (+ 2e-) to the right and side.

    Solution: 2H2O2 ==> H2O + O2 +2e-
    -2 -2


    I think the first way is right.

  • chem - ,

    He's right. When you reduce H2O2 in basic solutions you have to add OH- to balance the equation.

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