mariacchi
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if the oxidation state of an atom is an integer, when doing the redox half equations, do you have to multiply to make it an integer?

eg oxidation state of Cr = 2.5
of Cr 3+= +3
in the redox eqn: (Cr2O3)- ---> (Cr)3+ in acidic conditions
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LukeFranks0298
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I don't think you need to for this question. Just follow your usual rules: balance chromium on both sides, balance oxygen using water and then hydrogen using h+. I got an equation that had h+ on the left so I assume it is right (as the question says in 'acidic conditions').
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1st superstar
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Pigster might be able to help?
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Claisen
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Are you sure it's supposed to be an anionic complex? Fractional oxidation states are quite rare and aren't really supported by the IUPAC - they're also a formalism. It wouldn't make sense in terms of CFSE/MO for Cr to adopt a fractional oxidation state. Cr3+ is a high spin d3 tg2 complex and is very stable in this state. I think this is either some jargon question made up by a teacher or you've read it wrong.
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Pigster
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(Original post by mariacchi)
if the oxidation state of an atom is an integer, when doing the redox half equations, do you have to multiply to make it an integer?

eg oxidation state of Cr = 2.5
of Cr 3+= +3
in the redox eqn: (Cr2O3)- ---> (Cr)3+ in acidic conditions
You have made a number of threads about Cr2O3- recently and I agree with Claisen, I don't think it actually exists (although I wouldn't have put it quite so knowledgably as s/he did).

Fractional o.n. are rare. The only two that come to mind are Fe3O4 (which is really just a mix of Fe2+ and Fe3+) and Ag2F (which probably should only be described as Ag with a 0.5 o.n.)

IF (and that is a big if) Cr2O3- exists, its half equation to Cr3+ would be:

Cr2O3- + 6H+ -> 2Cr3+ + 3H2O + e-

i.e. as LukeFranks0298 points out, it is nothing special... just following the usual rules.
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