Balancing oxidatio-redox

[UIUCstudent]

MnO4(-) + Zn à MnO2 + Zn(OH)4(2-)
So the balanced version is
4H2O + 2MnO4(-) + 3Zn à 2MnO2+3Zn(OH)4(2-)+2OH(-)

Here's a gif for clarity
http://i45.photobucket.com/albums/f84/azncrombie/rxn.gif

I'm not sure why this is the balanced equation. The charges aren't balanced. I'm trying to solve this using the Bridge Method and got to the point where I know the coefficient of Mn:Zn is 2:3. Just have trouble knowing where to put hydroxide and water in the equation.

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[Isoprop]

I don't think it is balanced. For the MCAT, you won't have to balance equations other then to recognize that the charges must be equal on both sides and the number of each elemental atom is the same for both sides.

The exception is nuclear chemistry (radioactivity) where we don't care about charges so much (e.g. an alpha particle is rarely written with a +2 charge).

 

[BerkReviewTeach]

That's a typo in the new BR General Chemistry book.

It should have 4 OH- on the left side, and not 2 OH- on the right side. The half reactions are correct, but the summed up overall reaction has the typo.

 

[Catburr]

The exception is nuclear chemistry (radioactivity) where we don't care about charges so much (e.g. an alpha particle is rarely written with a +2 charge).

Those damn alpha particles. I actually missed a practice test question recently due to ignoring charge on an alpha particle...

Totally off topic, sorry. : )