Wolfram
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How do I separate NaNO2 from NaNO3?
Any ideas how to separate NaNO2 from NaNO3?
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Mumbles
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Well do you want both, or just one?
The first thing that comes to mind is fractional recrystalisation. I'd probably go with absolute ethanol for the recrystalisation.
NaNO<sub>3</sub>: 1g per 125 mL EtOH
NaNO<sub>2</sub>: 3g per 100 mL EtOH
As you can see, the nitrite is more than 3 times as soluble as the nitrate. I'd probably go with 2 recrystalisations to get which ever product
you want. In water solutions there are both quite soluble, so I don't think that would work as well, and you'd lose quite a bit or product.
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chemoleo
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alternatively, you could reduce all the present nitrate to nitrite, or, conversely, oxidise all nitrite to nitrate. If you are not happy with this,
just half the batch of nitrite/nitrate, and do an oxidation and reduction on each, respectively. Probably the most economic version 
[Edited on 13-10-2003 by chemoleo]
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Marvin
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Fractional crystalisation from a neutral solution in water.
Its probable the mixture is allready resulting from an attempt to reduce nitrate, so the reduction method is probably not useful.
[Edited on 14-10-2003 by Marvin]
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BASF
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alternatively, you could reduce all the present nitrate to nitrite
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And how exactly? - The choice of the reductant is not that easy.
Fe(II) for example would reduce the nitrate to ammonia.
But the idea of recrystallizing NaNO2 from absolute EtOH is a good one, i think.
One could make use of the Na2CO3/N2O3-method or just decompose NaNO3(yields NO2-/NO3- -mix) then.
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