Chemistry  DrBob222
posted by Alex on .
CH3OH + MnO4 > Mn2+ + CH2O
Earlier I posted this question and then realized that CH3OH didn't have a charge. It changed my work because the oxidation state changed. Can you check if what I fixed is correct?
CH3OH + MnO4 > Mn2+ + CH2O
1e/C 5e/Mn
x 5 x 1
= 5 = 5
5CH3OH + 1MnO4^ > Mn^2+ + CH2O
I now got a different coefficient for manganese. And now I need to balance it..
5CH3OH + 1MnO4^ > Mn^2+ + 5CH2O + 4H2O
I'm stuck. I know we have to add H+ ions to balance the H's but I don't know how much.

No. I don't remember the exact equation but I know the one I wrote for you that evening was correct. This one, the C has an oxidation state of 2 (4H=+4, 1 O = 2 so C must be 2) in CH3OH. It goes to zero on the other side with CH2O so it loses 2 electrons.
Mn changes from +7 to +2 so it is a gain of 5 electrons.
Multiply the C half equation by 5 and the Mn half equation by 2. Then add water to the right to balance the oxygen atoms, then H^+ on the left to balance the H atoms.
I get 6H^+ + 5CH3OH + 2MnO4^ ==> 2Mn^+2 + 5CH2O + 8H2O
Check my work. 
Ahh! You're right. I multiplied the H with the O instead of adding and ended up losing a 1 charge. Thanks so much for the help!