Upsilon
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I'm pretty sure I made nitric acid...
I began with a saturated solution of calcium nitrate (can be bought very cheaply as fertilizer) and added a stoichiometric amount of 98% sulfuric acid
according to this equation :
Ca(NO3)2 (aq) + H2SO4 (l) -> CaSO4 (s) + 2HNO3 (aq)
I filtered out the insoluble calcium sulfate, and threw a modern penny (copper plating) into the resulting solution. It took a long time for the
copper plating to start dissolving (I did this on a very small scale without appropriately-sized glassware, so I had to use more water than
necessary). Eventually the plating on the penny began developing holes and bubbles emerged. The solution began turning a pale blue, due to the
formation of copper nitrate.
I don't have an appropriate container to store nitric acid in currently, so I can't do this on a large enough scale to get a higher concentration. Has
anyone else tried this before/is willing to try it, and wants to share their results? I'd like to know if it is feasible to expect high concentrations
of nitric acid (50%+) this way.
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Pyro
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the produced CaSO4 is a bitch to work with, it takes forever to filter and fucks up your glassware if you happen to heat it. you should transform the
Ca(NO3)2 to NaNO3 or KNO3 before starting
all above information is intellectual property of Pyro.  |
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Upsilon
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Quote: Originally posted by Pyro  | | the produced CaSO4 is a bitch to work with, it takes forever to filter and fucks up your glassware if you happen to heat it. you should transform the
Ca(NO3)2 to NaNO3 or KNO3 before starting |
I only used calcium nitrate instead of sodium/potassium nitrate because calcium sulfate is basically insoluble in water, while sodium/potassium
sulfate are soluble and will be much harder to separate from the HNO3 solution.
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Zyklon-A
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Yes, I have done it before, I actually use barium nitrate mostly, as it is somehow cheaper for me to get, and the corresponding sulfate salt is less
soluble.
Getting near anhydrous nitric acid is possible on paper, but in reality, it's too hard to filter of so much solid (Ba/CaSO4) in proportion
to the small amount of liquid (nitric acid.)
I add an equal amount of water (by weight) to the sulfuric acid, this yields 77.77% nitric acid by weight, which is quite good.
[Edited on 24-3-2014 by Zyklonb]
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blogfast25
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| Quote: Originally posted by Upsilon | | [...] calcium sulfate is basically insoluble in water, while sodium/potassium sulfate are soluble and will be much harder to separate from the HNO3
solution. |
Calcium sulphate is better described as 'very poorly soluble'. Your nitric acid is slightly contaminated. Just evaporate a bit of it to dryness...
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Zyklon-A
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Yes, barium sulfate is less soluble: 0.0002448g/100 mL at 20 °C, Vs. calcium sulfate: 0.21g/100ml at 20 °C.
Quite a bit of difference.
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Upsilon
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But barium nitrate is also drastically less soluble than calcium nitrate...doesn't that mean you need more water to completely dissolve it, reducing
the concentration of the final product?
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blogfast25
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| Quote: Originally posted by Upsilon | | But barium nitrate is also drastically less soluble than calcium nitrate...doesn't that mean you need more water to completely dissolve it, reducing
the concentration of the final product? |
Not necessarily, no. Precisely because BaSO4 is so insoluble you can treat even a slurry of Ba(NO3)2 with H2SO4 and still make nitric acid that way. A
waste of a perfectly useful barium salt, if you ask me, but each to their own.
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Töilet Plünger
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This was used in a distillation, the video is here.
http://www.youtube.com/watch?v=7akk5ppJjEw
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Zyklon-A
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| Quote: Originally posted by Upsilon | | But barium nitrate is also drastically less soluble than calcium nitrate...doesn't that mean you need more water to completely dissolve it, reducing
the concentration of the final product? |
Like blogfast25 said, the insolubility of barium nitrate drives the equilibrium nearly completely to the right: H2SO4 +
Ba(NO3)2 → 2HNO3 + BaSO4↓.
The solubility data I mentioned above is of course for water, not dil. nitric acid, but I'm pretty sure it's nearly insoluble in both.
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Upsilon
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Another question: can I store nitric acid in an empty plastic hydrogen peroxide brown bottle without any issues?
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DraconicAcid
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| Quote: Originally posted by Upsilon | | Another question: can I store nitric acid in an empty plastic hydrogen peroxide brown bottle without any issues? |
You're better off storing it in glass.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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HgDinis25
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It depends on the type of plastic. HDPE usually stands most acids (even 98% sulfuric acid). For Nitric acid with a concentration <70% HDPE and even
PE will do the job.
It is advised against storing corrosive substances (unless those that corrode plastic) in glass because it can easilly break and release the contents
(bull**** for me, but posting the recomendation anyway).
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Upsilon
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| Quote: Originally posted by HgDinis25 | It depends on the type of plastic. HDPE usually stands most acids (even 98% sulfuric acid). For Nitric acid with a concentration <70% HDPE and even
PE will do the job.
It is advised against storing corrosive substances (unless those that corrode plastic) in glass because it can easilly break and release the contents
(bull**** for me, but posting the recomendation anyway). |
I looked on the bottom and it is in fact HDPE. The brown bottle will also help combat light decomposition, so that's a bonus.
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HgDinis25
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The UV decomposition of <70% Nitric Acid is negligible. Only above those concentrations the HNO3 will start decomposing (at a very very very slow
rate) into nitrogen oxides:
4 HNO3 → 2 H2O + 4 NO2 + O2
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blogfast25
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I get mine (5 L of 70 w%) delivered in HPDE jerrys. No problems whatsoever.
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hyfalcon
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The cap may be an issue though.
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ElizabethGreene
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| Quote: Originally posted by Upsilon |
I looked on the bottom and it is in fact HDPE. The brown bottle will also help combat light decomposition, so that's a bonus. |
Please label this bottle in the most terrifying manner possible. It would be horrific if someone attempted to use Nitric acid to clean an open wound.
Ouch.
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