barley81
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Nitric acid color
I poured about 300mL of colorless 70% ACS nitric acid into a glass bottle w/glass stopper lubricated with a small amount of vaseline. The bottle was
clean and dried (rinsed with acetone to speed it up), but a very small amount of white film was on the bottom. Then, I wrapped it in translucent foam,
put it in an HDPE plastic bottle with the top cut off (just fit, no extra room) and packed the top with paper toweling. Then I stretched a few layers
of paper over the top and taped it shut. The acid was left on my workbench inside, below a small window, for about a week and a half. After, it was
taken out and had turned yellow(with a green tinge due to the glass). Is the color because of NO2 from sunlight, trace amounts of oxidized vaseline,
or the whatever was in the white film? I'm thinking the acid oxidized a tiny amount of vaseline and was reduced to NO2. Should I degrease the stopper
and store in a dark place?
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antibody
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NO2 is a reddish/brown colour. More likely your Nitric acid reacted with something.
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hkparker
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It will appear yellow in low concentrations. My nitric acid is stored in a very dark location and over time it has gone from clear to slightly
yellow, to a bit orange with a haze above it. While a reaction with vasoline is also likely (nitric acid fumes travel in their containers) this color
is normal for nitric acid. Keeping it out of the light will slow how long it takes.
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"Nothing is too wonderful to be true if it be consistent with the laws of nature." -Michael Faraday
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The WiZard is In
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Quote: Originally posted by barley81  | | I poured about 300mL of colorless 70% ACS nitric acid into a glass bottle w/glass stopper lubricated with a small amount of vaseline.
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Well.... my Conc HNO3 which has been stored out-of-doors
year round for 15+ years — when left in the sun for a hour or
so turns light oxide of nitrogen brown. I still wouldn't drink
bath in it other then that it seems to be chemical usable.
djh
----
As if ordained by Fate, Nitre, that admirable salt,
hath made as much noise in Philosophy as in
War, all the world being filled with its thunder.
John Mayow
Ttractalus Quinque Medico-Physici, 1674
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Fleaker
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Once I added RFNA to 70% nitric acid and was left with a brilliant green-blue solution. I wonder if the concentrated acid some how oxidized the weaker
acid? Anyone else notice this phenomena?
Neither flask nor beaker.
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--The Dark Lord Sauron
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starman
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I also have a clear reagent bottle (I have no amber) with 70% HNO3 that has discoloured over time.My understanding is(I haven't tried it) is aerating
the the acid will clear the disolved NOx.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
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barley81
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I just noticed that the acid has brown NO2 gas above the liquid. I'll let it sit in the dark from now on, maybe it'll clear up. If that doesn't work,
I'll try aerating it as suggested. Thank you all for your answers!
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mr.crow
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My reagent grade acid is fine sitting in the dark. Comes in a clear bottle.
So I made some RFNA and added it to water to make a 70% solution. Of course it got very hot and decomposed a little. The solution is still piss yellow
and has a slight color above the solution.
How do I make the solution clear? Don't think we got a solid answer here.
[Edited on 26-6-2011 by mr.crow]
Double, double toil and trouble; Fire burn, and caldron bubble
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ItalianChemist
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| Quote: Originally posted by mr.crow |
How do I make the solution clear? Don't think we got a solid answer here.
[Edited on 26-6-2011 by mr.crow] |
by vacuum distillation
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woelen
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Nitric acid discolors anyway, when its concentration is well above 65%. I have a bottle of 70% nitric acid and I store this in the dark. Still, it has
a slight yellow color:
http://commons.wikimedia.org/wiki/File:Nitric_acid_70_percen...
[Edited on 26-6-11 by woelen]
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mr.crow
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Looks pretty clear to me.
Thanks for all the great pictures on Wikipedia too
Double, double toil and trouble; Fire burn, and caldron bubble
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