[musicman92]

Hey everybody,

In C₂H₄, the oxidation number for C is -2 and for H it's +1, right?
Well what would they be in C₂H₄⁺?

Also, for MnO₄^-, would the oxidation number for Mn be +7, and for O it would be -2? I'm guessing that's right cause it has to have a 1- charge, right?

thanks

[sjb]

Hey everybody,

In C₂H₄, the oxidation number for C is -2 and for H it's +1, right?

How did you reach that conclusion? What's wrong with, e.g. C being +2 and H, -1?

Well what would they be in C₂H₄⁺?

Also, for MnO₄^-, would the oxidation number for Mn be +7, and for O it would be -2? I'm guessing that's right cause it has to have a 1- charge, right?

thanks

The latter is a reasonable conclusion to draw.

[musicman92]

ook? yeah, ok, C as +2 and H as -1 makes more sense then.
But if I have H as -1 what would C be to give the compound an overall 1+ charge?

[sjb]

I wasn't saying you were necessarily wrong Oxidation states to my mind only really have much use when the atoms have quite a large difference in electronegativity, so between carbon and hydrogen it's not really that much of a difference.

Let's run with H as -1 for now, perhaps you can do a similar thing for H as +1.

C₂H₄⁺ has a total "oxidation state" of +1, so the C₂ unit will have a total oxidation state of +5 (+1 - -4), so carbon has an oxidation state of what here?

[musicman92]

I wasn't saying you were necessarily wrong Oxidation states to my mind only really have much use when the atoms have quite a large difference in electronegativity, so between carbon and hydrogen it's not really that much of a difference.

Let's run with H as -1 for now, perhaps you can do a similar thing for H as +1.

C₂H₄⁺ has a total "oxidation state" of +1, so the C₂ unit will have a total oxidation state of +5 (+1 - -4), so carbon has an oxidation state of what here?

that's what i thought: that the total of the carbon will have to be +5. but how do you get +5 out of C₂? or am i missing something here...

[Borek]

how do you get +5 out of C₂?

Whichever way suits you - 2+3, 2*2.5, 7-2

Seriously - oxidation numbers don't reflect any real property of the atoms, in some situations they can be assigned any way you like. 2+3 or 2*2.5 seem the most logical here, but I would risk stating one of these is 'correct' and the other is not.