Balancing equation in basic solution

[vaazu]

[SOLVED] balancing equation in basic solution

Homework Statement

The alkaline solution of hypochlorite ions reacts with solid chromium(3)hydroxide to produce aqueous chromate ions and chloride ions. Write the net ionic equation for the reaction.

Homework Equations

The Attempt at a Solution

bone:
ClO(-)+Cr(OH)3=CrO4(2-)+Cl(-)
ox:
Clo(-)=Cl(-)
ClO(-)=Cl(-)+H2O
ClO(-)+2 H2O=Cl(-)+H2O+2 OH(-)
ClO(-)+H2O+2e(-)=Cl(-)+2OH(-) | *3
red:
Cr(OH)3=CrO4(2-)
Cr(OH)3+3H2O=CrO4(2-) (should be 1 H2O)
Cr(OH)3+3H2O+9OH=CrO4+9H2O
Cr(OH)3+9OH-3e=CrO4+6H2O | *2
after adding them together
3ClO+2Cr(OH)3+12OH=3Cl+2CrO4+9H2O

both my equation and the answer in my book are balanced but the book answer has 4OH and 5 H2O, but mine 12 OH and 9 H2O. What did I wrong or how can I cancel some of the H2O-s and OH-s?

Never mind found the problem..

 

[Nino MMP]

Instead of adding the two equations I should have subtracted them. So the final equation should be3ClO+2Cr(OH)3+9OH=3Cl+2CrO4+4H2O

 

[Blueshift5]

I didn't fully balance the water molecules in the redox reaction. The correct equation should be:
3ClO + 2Cr(OH)3 + 12OH- = 3Cl- + 2CrO4-2 + 9H2O