Oxidation numbers and balanced equations

[Rach83]

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I just completed a AAMC test and in one of the questions it asks for oxidation numbers of a certain element before and after a reaction (When sulfuric acid reacts with copper, how does the oxidation number of the sulfur change?).

I thought that in order to even begin figuring out oxidation numbers, balanced equations were required but in the solutions, they use
H2SO4→ SO2.

I ended up with the right answer but lost some time trying to balance. Is balancing of all molecules (Cu included) unnecessary?

 

[Vanguard23]

Oxidation numbers should be independent of stoichiometry.

 

[Rach83]

Oxidation numbers should be independent of stoichiometry.

great, thanks!😀

 

[Vanguard23]

Overall balancing of charge is not, iirc.