pneumatician
Hazard to Others
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Registered: 27-5-2013
Location: Magonia
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Mood: ■■■■■■■■■■ INRI ■■■■■■■■■■ ** Igne Natura Renovatur Integra **
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nitric acid expired?
I have a bottle half full of nitric acid @ 65% WELL STOPPED, no corrosion around... The expire data is 9/2014. Opened very few times. I put some in a
250ml bottle for everyday use, so the half full bottle rest untoched some years. Today I put some over iron and, no smell, no reaction... What the
hell happened? where is my gas nitric acid?
Many if not all chems have a expiration date, but well stopped, in a dark and cold place... salts, acids... with expiration date?
No, when I opened the bottle NO, a lot of gas not excaped!
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DraconicAcid
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Location: The tiniest college campus ever....
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Doesn't nitric acid passivate iron? I can't imagine that it would actually go bad, or that the acid would have all evaporated. Try it with some
copper.
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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woelen
Super Administrator
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Registered: 20-8-2005
Location: Netherlands
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Nitric acid does not go bad. Even if not properly sealed, its concentration does not go down noticeably. It can cause corrosion of nearby materials
though if not properly sealed.
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chornedsnorkack
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Nitric acid does have a spontaneous decomposition reaction:
4HNO3<->4NO2+2H2O+O2
It is an equilibrium reaction and the reverse is standard production route for nitric acid.
At 65 %, what is the long term equilibrium concentration of NO2 in solution and headspace? If the acid has been purified of NO2
and then kept in cool and dark conditions, how quickly is the equilibrium with NO2 restored?
[Edited on 9-5-2020 by chornedsnorkack]
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Tsjerk
International Hazard
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Registered: 20-4-2005
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I found a small bottle of 53% HNO3 in my storage I forgot about. It probably has been there for 12 years but when I measured the density it was spot
on and the reaction with copper over a couple of days gave a near complete reaction.
The storage has been fluctuating between 1 degree and 30 degrees over the years.
The bottle was capped with Teflon tape. I wouldn't be worried as long as the bottle is sealed properly.
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