Posted by Alex on Monday, February 18, 2008 at 2:24pm.
I don't believe the CH3OH has a charge on it.
6H^+ + 5CH3OH + 2MnO4^- ==>2Mn^+2 + 5CH2O + 8H2O. Check it to make sure it balances BOTH with atoms and charge.
Oh no..it doesn't. I misread it because of the print. Wouldn't that change the whole thing? I don't think it would have a coefficient of 5 anymore. I'm balancing redox equations. And now since the overall charge has changed, the charge on the carbon has changed, and so the oxidation has changed.
You are right and no, you're not right. Sound confusing?
I balanced the equation as if the negative charge on the CH3OH was NOT there so my equation is correct, I think. You are right that a negative charge there, or is one WAS there and you took it off, it would change the oxidation states; however, C would still be oxidized and Mn still is reduced. Here is the way you do those redox equations.
Mn goes from +7 on the left to +2 on the right. That is a gaiin of 5 electrons and it is reduced.
C on the left, in CH3OH, has an oxidation state of -2. It goes to 0 on the right in CH2O. That is a loss of 2 elecrons which makes C oxidized. 10 is the lowest common multiple, so multiply Mn by 5 and CH3OH by 2 which gets 10 elecrons gained and 10 electrons lost. Now add water to the right side to balance the O atoms, then add H ion on the left to balance H atoms. Then check to make sure the charge balances. I just check it one more time and all atoms balance. All charges balance.
Check that. I made a big typo. The manganese half equation is multiplied by 2 and the CH3OH/CH2O half equation is multiplied by 5. The equation is wrote is balanced, both with atoms and with charge but I mistyped the coefficients in the explanation.