April 27, 2015

Homework Help: chem

Posted by Chris on Monday, January 15, 2007 at 2:39pm.

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.

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