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Saber
alias Picric-A
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Storage of Fuming Nitric acid
Every time I required Fuming nitric acid in the past, I would make it in situ by distill a mix of NaNO3/H2SO4. The only reason I did this is I don’t
have any bottle strong enough to withstand the fuming acid. As many of you know, when you need it on a day to day basis this gets very tedious! What I
hate the most about this is it develops quite some NO2, which, although I have a perfectly good hood, I still don’t like working with.
As a result of this I have decided I would like to make a large batch of the acid and store it. I have a number of questions on this however;
Firstly the acid decomposes into O2, does this mean there will be a significant pressure buildup, every time I open/close the bottle?
Secondly, is it better to store WFNA or RFNA? My guess is WFNA as it is less oxidizing but this is a mere guess.
Finally has anybody else bought fuming nitric acid from a supplier? If so, what type of bottles does it come in? and what is the screw cap like? Eg,
glass?
I have read storing any type of <80 nitric acid in aluminum is fine. Is this true?
Reference- http://pubs.acs.org/doi/abs/10.1021/ac50095a010
Thanks,
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Jor
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I have heard WFNA decomposes much more easiliy, and is a greater storage hazard.
You have 2 choices:
-PTFE/Teflon bottles
-Thick glass bottles with PTFE liners (preferabely DURAN).
Member Fleaker has recommended:
http://shop.ebay.com/merchant/billye46
I have bottles with release vents, wich release overpressure. I use this to transport my waste safely, as I give it to another chemist who throwns it
in their waste container in their lab. Try to find one of these.
Why is NO2 a problem in a hood? Even a simple homemade hood will simply get rid of nitrous fumes easiliy, and these are not really dangerous anymore
with a fume hood.
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hissingnoise
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HNO3 stored in Al containers has had an inhibitor (HF) added to protect the Al.
Merck safebreak bottles are good as the screw-caps (PE) have a teflon insert which effects an airtight seal when tightened. . .
Stored in a cool, dark place, HNO3 decomposition is slow and pressure build-up minimal.
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DJF90
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hissingnoise: Very concentrated nitric acid will passivate aluminium and hence will not require an inhibitor. If I were to store it personally, it
would be in an amber bottle with a PTFE lined cap and kept in a cool dry place, as many chemicals should generally be stored.
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Fleaker
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Saber, get one of those FEP bottles if you want to store it. You should store RFNA rather than WFNA, in the dark. It will store for years.
Also, those FEP bottles can be used to store all the oleum you make with your contact process (which I still want to see).
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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hissingnoise
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In commercial practise IWFNA/IRFNA is preferred---the fluoride may form a tougher passification layer than the oxide. . .
I'm guessing, though!
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panziandi
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If I were you I would store RFNA and store it in an amber glass bottle with a teflon lined PE lid. Store that bottle in the dark and cool, preferably
inside a secondary container.
RFNA has a fair amount of dissolved NOx which displaces the equilibrium of nitric acid breakdown to the left. WFNA can be readily made from RFNA, when
required, by passing a brisk current of warm, dry air through the acid to remove the dissolved NOx.
Indeed, commercially HF is added to FNAs to passivate the metal containers with a F layer. Concentrated nitric acid does indeed passivate some metals,
but HF passivation is better.
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benzylchloride1
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I store my white fuming nitric acid in a pyrex glass stoppered nitric acid bottle. The stopper seals well and I have not had a problem. I store less
then 100 mL at a time.
Amateur NMR spectroscopist
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Picric-A
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Why dont you just make it as and when needed?
that way you dont have to worry about overpressure/corrosion ect...
If not use an pure aluminium bottle and gas the FNA with some anhydrous HF so its around 1%.
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Lambda-Eyde
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>96 % white fuming nitric acid is commonly stored in amber bottles with fluoropolymer lined caps, even in schools.
As long as it is stored like that and in a cool place, I don't think there would be any problems.
If you want to be really sure, you could probably relieve the pressure once a week.
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Picric-A
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Relieveing pressure would release a cloud of toxic/corrosive fumes, along with weakening the acid, and most of all be a pain to do it weekly!
just make it as and when needed!
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DJF90
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Do you not read the thread... He said he was tired of making it when needed! And it would be less of a pain to release pressure weekly than to have to
make it every day. Just when I thought we got rid of an idiot you turn up again. Great.
[Edited on 14-6-2009 by DJF90]
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Ozonelabs
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We keep ours stored in the original BDH container-
That is kept in a large HDPE screw top container which has Sodium Carbonate at the bottom.
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hissingnoise
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Pressure release isn't necessary at normal temperatures---decomposition of HNO3 produces NO2 + H2O and NO2 promptly dissolves. . .
Below 0*C decomposition is practically Zero.
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DJF90
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That bottle looks strangely blue... Is that how it actually is?
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UnintentionalChaos
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Quote: Originally posted by hissingnoise  | Pressure release isn't necessary at normal temperatures---decomposition of HNO3 produces NO2 + H2O and NO2 promptly dissolves. . .
Below 0*C decomposition is practically Zero. |
You have an unbalanced equation there.
4HNO3 --> 4NO2 + 2H2O + O2
It's the oxygen gas that pressurizes the container, not the NO2.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Ozonelabs
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Yes, it is actually that blue.
The bottle is actually a bottle in a bottle. The one that is in direct contact with the acid is opaque and blue, there is a solution of some
description between the two layers of plastic and the outer layer is clear plastic.
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hissingnoise
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Ooops! Yes, I must be getting Oldtimer's---but O2 too dissolves to a large extent.
The pressure generated certainly isn't enough to be a problem at normal temps. . .
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Saber
alias Picric-A
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Thanks for all your replys,
@ Picric-A - If you hadnt picked up fag ends and read the rest the rest of the thread you will of read me saying how i do not want to keep generating
it in situe, so yes i want to store some.
@Ozone- Nice bottle you have there! whats the cap made of? just thick PTFE or glass?
I am searching for a place to buy PTFE bottles, as they would be extremly usefull, not only for fuming nitric buy for HF also.
until then i may just store it in a quickfit flask as benzylchloride1 mentioned.
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panziandi
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Saber - The lid on that safe break bottle is likely PE with a PTFE liner.
You can pick up cheap glass bottles with ground glass stoppers on eBay (sometimes with Nitric Acid engraved on them!) if you check lab supplies,
failing that try searching for "pharmacy bottles" or "poison bottles" may get something useful that way?
As to PTFE bottles... these are VERY expensive! IIRC a 15mL one would have set me back about £12! Instead, opt for a HPDE bottle for HF with a PTFE
lined PE lid. These are quite suitable for HF solutions including 48% stuff. I personally wouldn't store FNA in PTFE bottles, they are bad to grip for
starters, but also its just overkill IMHO.
How much do you think you will make in one go to store?
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Jor
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Saber, are you seriously considering having HF in your home lab?
This stuff is very dangerous! I wish i could have it, as it is so interesting, but the hazards are too great!
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Ozonelabs
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Saber- I will inspect the bottle the next time I'm at the lab and let you know.
Jor- Following our P.M.'s it is possible to keep and use HF safely in a 'home' lab. We do- and there have been no incidents.
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Jor
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| Quote: Originally posted by Ozonelabs | Saber- I will inspect the bottle the next time I'm at the lab and let you know.
Jor- Following our P.M.'s it is possible to keep and use HF safely in a 'home' lab. We do- and there have been no incidents. |
Yes Ozonelab, you are indeed an exception. You work with fume hood, thick gloves, lab coat, shield, Ca-gluconate gel, and most importantly, with 2
persons! Working alone with HF is not so smart.
I can imagina that only very few people can follow these critical precautions on working with HF.
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Formatik
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If you store the fuming HNO3 in a glass bottle with a glass stopper, then you shouldn't have to worry about overpressure accumulation. I think in this
case if you kept the stopper loose that too much pressure inside would push the stopper up, before the bottle would reach the point of bursting.
I haven't tested it out with large amounts, but had a few bottles of a testing acid for goldsmithing in brown glass small bottles and glass stopper,
judging from the red color of the acid and fumes seemed like RFNA. Those were stored for years in the dark and never burst.
Btw, tin has very good resistance (much better than aluminium, even at elevated temperature) according to this paper: http://pubs.acs.org/doi/abs/10.1021/ie50466a021 Gold and tantalum too, but who cares about those.
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hissingnoise
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This is the Merck Sb bottle---this acid has been stored at temps close to 30*C and no outrush is noticed on opening.
Once in the bottle with the cap tightened you can forget it till it's needed. . .
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