Oxidation Number (1 Viewer)

[housemouse]

My teacher has no idea how to get an oxidation number of +4 for SO2.

Could some explain how SO2 has an oxidation number of +4??

 

[Riviet]

Sulfur dioxide has a overall charge or valency of zero, therefore the sum of the oxidation numbers (hereafter ON) of sulfur and oxygen must add up to 0. Now, remember that oxygen has an ON of -2 in compounds. We have two of these in SO₂, so the total oxygen state of 0₂ is 2 x -2 = -4. But the sum of the oxidation numbers needs to add to zero, therefore to balance this, the ON of sulfur in SO₂ has to be +4. I hope that helps.

 

[sando]

haha. Riviet knows what to do, but that guys teacher doesnt

 

[housemouse]

So we only look at the last bits i.e. ignore the S?

 

[Riviet]

So we only look at the last bits i.e. ignore the S?

SO₂ itself has a valency of 0, the sulfur in it has an ON of +4. Your teacher meant to ask "what is the oxidation number of sulfur in sulfur dioxide?"

 

[Kmahal1990]

The part that worries me is that your chemistry teacher does not know to work out the oxidation state.