letseathydrazine37
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Separation of Ammonium Nitrate and Potassium Chloride
Hi all,
So I was attempting to synthesize potassium nitrate from the metathesis of ammonium nitrate + potassium chloride in water. Well that experiment
failed, likely due to my decidedly unstoichiometric (lil' bit of this, lil' bit of that) amounts of reagents. But that is not why I am here.
My problem arises from a mistake I made in the process, and to keep a long story short, I now have a cereal bowl sitting in front of me partially
filled with a mixture of ammonium nitrate and potassium chloride, both in solid form. I decided, instead of simply throwing it out, that I would
attempt to separate the two in the name of science!
But that's where I have run into some obstacles. My first thought was to try and dissolve one of the reagents in a solvent, but as far as I know both
NH4NO3 and KCl are easily soluble in the common solvents I have lying
around (Acetone, 91% Isopropanol, water), so unless someone knows of some special solvent that only dissolves one, that's kinda out of reach.
I considered melting the ammonium nitrate under moderate heat and somehow decanting it from the solid potassium chloride, but my understanding is that
there's quite a small range of temperature that liquid A.N. can exist at without becoming dangerously unstable. So that option kinda spooked me off.
D:
So does anyone out there have any ideas for me? The total volume of solids is only about 25mL, to give an idea of scale. Help is appreciated 
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bbartlog
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| Quote: | | as far as I know both NH4NO3 and KCl are easily soluble in the common solvents I have lying around (Acetone, 91% Isopropanol, water)
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KCl is insoluble in pure acetone. It's also scarcely soluble in ethyl alcohol (either 0.02 or 0.08g in 100cc at room temperature... Seidell
contradicts himself), and very likely to be rather insoluble in isopropyl alcohol as well, IMO.
I don't have any figures handy for the solubility of ammonium nitrate in acetone, so I don't know whether that helps. But hot (near-boiling) ethanol
will dissolve ~9g of ammonium nitrate per 100ml. Best suggestion off the top of my head is dissolve your powder in 200(?)ml of hot ethyl alcohol, then
filter hot (preferably using preheated filter). Most of the ammonium nitrate should dissolve, the KCl should be left behind.
You could also experiment with the solvents you have. If some of your stuff dissolves in hot acetone, you will know it's not the KCl.
[Edited on 17-9-2011 by bbartlog]
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letseathydrazine37
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Hmm, looking it up it seems KCl apparently isn't effectively soluble in alcohols. Must have been thinking of something else I guess. But your advice
worked quite well, I got some ethanol and sure enough the ammonium nitrate dissolved in it. Heating it was kind of a problem, but my truck's still
hot engine seemed to work fine (totally ghetto, I know, but I have no hot plate and I'm not about to put that near open flame)
From what I could tell, a small sample of the powder revealed that the ammonium nitrate did not seem to be soluble in acetone either, though I don't
know if the anti-caking agents on it had anything to do with that or if A.N. simply isn't very soluble in it. But the flask was quite full of acetone
and there was no visible change of the amount of A.N. in the mixture.
Anyway, thanks for the help. Now I've got a crapload of ethanol to evaporate! D:
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