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Can someone please explain to me something here please? In this oxidation problem

Na2Cr2O7 + HNO3 + Na2SO3 yields NaNO3 + Cr(NO3)3 + Na2SO4 + H2O

I know S is Oxidized and Cr is Reduced. However, when I look at the solution set, I am get completely confused.

They are putting

SO3^2- yields SO4^2- for oxidation and for reduction they have Cr2O7^2- yields 2 Cr ^ 3+.

I understand how to get what is Oxidized and what is reduced.

However, I am having trouble knowing what to eliminate. How can they just get read of the Na2 in the first one and (NO3)3 in the second one? Is there some sort of rule that tells you what you can get rid of? Also, once they do get rid of half of the original ion, how do they assign the charge? Is the charge just the polyatomic charge of sulfite and sulfate?

Thanks in advance

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# Homework Help: Having difficulty with Ox-Redox

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