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Dissolving MnO2 with HNO3 [Mar. 6th, 2011|11:14 pm]
Chemistry Help


I ask a lot of questions and you all are always very helpful. (:

We recently had a lab where we used diluted HNO3 to clean a filter that we had collected MnO2 from. Why was HNO3 used when MnO2 is insoluble in nitric acid?

Someone showed me this reaction:

2MnO2 + 4HNO3 -> 2Mn(NO3)2 + 2H2O

which does not make sense to me since Mn(IV) is being reduced to Mn(II), but I don't see anything being oxidized. What am I missing here?

Thanks in advance for any help/insight.

[User Picture]From: manfrommlwkee
2011-03-07 02:50 pm (UTC)
I don't think your equation is balanced. I think the typical reaction for doing this also involves oxalic acid as a reactant and liberates carbon dioxide as a product.
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[User Picture]From: doubtmars
2011-03-16 02:52 am (UTC)
It isn't. (: This reaction was given to me by someone else, but it didn't make sense to me.

I read about the oxalic acid looking through the textbooks and online, but we didn't use that in the lab.

Thank you for responding.
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[User Picture]From: superhimik
2011-03-19 11:44 am (UTC)
I don't know the proper English equivalent, in Russian it is "реакция раскисления": MnO2+HNO3=Mn(NO3)2+O2+H2O.
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[User Picture]From: superhimik
2011-03-19 11:54 am (UTC)
by the way, concentrated HNO3 will be much more effective.
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