[omfgwtfcamelbbq]

I'm having trouble with one question balancing it by using the half equation method.

SO3(2-)+ MnO4(1-) = SO4(2-)+Mn(2+)

Heres what i have so far

1) Write half equations...

SO3(2-) = SO4(2-)
MnO4(1-) = Mn(2+)

2) Balance oxygen using H2O

SO3(2-) + H2O = SO4(2-)
MnO4(1-) = Mn(2+) + 4H2O

3) Balance Hydrogen using H+ ions.

SO3(2-) + H2O = SO4(2-) + 2H(1+)
MnO4(1-) + 8H(1+) = Mn(2+) + 4H2O

4) Balance net charges on both sides of each half equation

Heres where i get stuck... to balance right hand side of half equation would require taking further electrons. Im wondering do i add 2 Hydrogen ions to even out balance then re balance hydrogen on both sides?

[Borek]

You may add electrons on whichever side of the equation they are needed - note that reduction half reaction must have electrons added on different side of the equation then oxidation.

[omfgwtfcamelbbq]

My problem is that

SO3(2-) + H20 = SO4(2-) + 2H(1+)

check left hand side... how do i balance it by adding electrons??? add negative electrons???

is it the question is wrong or ive stuffed something up?

[Borek]

So add electrons on the RHS and it will be OK. I told you - you may add them on either side.

Besides, adding "negative electrons" on the LHS is nothig else as subtracting them. Think in terms of algebraic operations - while it is not algebra, some rules still hold

[omfgwtfcamelbbq]

dont you see the problem... the right hand side is even charged already which is great!

the left hand side however has a overall -2 charge. To counteract im meant to add electrons... which will make it further negative.

Unless do you mean both sides just have to have the same charge?
And does it mean all sides of both half equations?

[AWK]

SO3(2-) + H2O = SO4(2-) + 2H(1+) + 2e(-) oxidation - electrons on the right side
MnO4(1-) + 8H(1+) + 5e(-) = Mn(2+) + 4H2O reduction - electrons on the left side
now we multiply the first equation by 5, and the second one by 2, and add both by sides
5SO3(2-) + 5H2O + 2MnO4(1-) + 16H(1+) + 10e(-) = 5SO4(2-) + 10H(1+) + 10e(-) + 2Mn(2+) + 8H2O
and finally
5SO3(2-) + 2MnO4(1-) + 6H(1+) = 5SO4(2-) + 2Mn(2+) + 3H2O

[Borek]

Unless do you mean both sides just have to have the same charge?

Yes - for each equation charge on both sides must be the same. Note that it doesn't differ from mass balance - ie equation is balanced when you have the same number of atoms on both sides of the equation. Same for charge, just you may have negative charge while you can't have negative atoms. Otherwise it is exactly the same.