[WahooMan]

I need some help balancing half equations. Here are the steps my professor gave me:

1. Write oxidation numbers, balance element that is being oxidized or reduced
2. Balance oxidation number of oxidized or reduced element by adding electrons
3. Add hydrogen atoms to balance the equation
4. Add water molecules to the equation to balance hydrogen atoms
5. Make sure the equation is completely balanced

Can someone take me through step by step and explain what exactly I'm supposed to do? Here is my first problem:

VO⁺² (aq) V⁺³ (aq)

Here is my attempt at the solution:

V is the element being oxidized.

The oxidation number of oxygen is always -2, so if the net charge of the VO molecule is +2, then the oxidation number of V on the left side of the equation must be +4, correct?

I added one electron to the right side of the equation to balance the oxidation numbers.

That takes care of steps 1 and 2, but I'm not sure how to "add hydrogen atoms to balance the equation" in step 3. Help?

[UG]

I'm going off on my own here, I haven't followed your professors instructions but we should get the same in the end (hopefully)
For your problem

VO⁺² (aq) V⁺³ (aq)

1. Balance all of the atoms which are not oxygen or hydrogen. There is no need to here.
2. Balance oxygen by 'adding water'

VO⁺² (aq) V⁺³ (aq) + H₂O (l)

3. Balance hydrogen by adding H⁺

VO⁺² (aq) + 2H⁺ (aq) V⁺³ (aq) + H₂O (l)

4. Balance the charges on each side

VO⁺² (aq) + 2H⁺ (aq) + e^- V⁺³ (aq) + H₂O (l)

[Borek]

3. Add hydrogen atoms to balance the equation

It sounds incorrect to me. As UG have shown, you should use H⁺ cations, not atoms.