Bedlasky
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Experiments with concentrated nitric acid
Hi.
I have access to concentrated (more than 98%) nitric acid. Are there any interesting experiments with this chemical? These are ideas which comes to my
mind:
1. Comparison of dissolving piece of copper wire in 54%/99% HNO3.
2. Reaction with small amount of halide salt (KCl, KBr, KI)
3. Action of 99% HNO3 on piece of paper tissue
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MrHomeScientist
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Nitrile gloves react rather violently to concentrated nitric. Good demonstration of why you need to pick the right glove material for the job!
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Sulaiman
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more than 98% w/w nitric acid is extremely concentrated, (WFNA)
'concentrated' nitric acid usually means 'azeotropic' nitric acid, about 68% w/w.
so you have access to nitric acid suitable for nitrations, a valuable resource.
Copper (or silver) pieces/lumps/coins initially show very little reaction rate,
then after a while the reaction becomes frighteningly accelerated,
rapidly bubbling, green froth forming, brown gas generating mayhem.
(if a little water is added the reaction occurs sooner)
so take care.
You could keep the copper nitrate solution for later use,
one use is to boil to dryness then heat to >>180oC to form CuO and lots more brown gas.
Copper nitrate is very soluble in water and not suitable for crystal growing or disposal down the drain.
You could try to capture the NO2 gas released (water or better, H2O2) to make more nitric acid,
but the reaction can be so violent that I would not attempt it.
Some metals such as iron, aluminium and chromium get passivated when exposed to conc. nitric acid.
I'm tempted to say 'eye protection is mandatory', but they are your eyes so its up to you.
As above, many glove materials are worse than useless when working with conc. nitric acid.
A little nitric acid on the skin then washed off will rarely cause long term harm,
just a temporary yellow stain.
A whiff of NO2 may make you cough but you will be ok,
a lung-full will possibly kill you.
P.S. https://en.wikipedia.org/wiki/Nitrocellulose
[Edited on 12-2-2020 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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woelen
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If you have P4O10, then you can try to make N2O5 by carefully distilling that from a mix of P4O10 and HNO3. N2O5 is a solid, which sublimes at 50 C or
so and can be distilled in an all-glass apparatus. It is very reactive and allows one to make certain anhydrous nitrates, which cannot be made from
nitric acid and which cannot be dehydrated without losing HNO3 and formation of basic nitrates. Be careful though, N2O5 is rather nasty stuff and very
reactive. Know what you are doing. It can decompose very violently to NO2 and O2.
You also have to be very careful with 98% nitric acid. Getting 98% acid on your skin is a lot different from getting standard concentrated 65% acid on
your skin.
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Bedlasky
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Thanks all for suggestions.
Sulaiman: Don't worry. I never did experiments with this stuff, but I work with it really often, so I know about all risks. When I work with it I
always wear goggles and shield.
Woelen: This would be really interesting, sadly I have acces to only very small amount of this acid, I don't have any P4O10 and don't have
distillation apparatus.
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woelen
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For small demo-experiments, which demonstrate its properties you could do the following:
- Take 1 ml of iso-propyl alcohol (very common, easy to obtain) and drip 0.5 ml of acid in this --> this will lead to an extremely violent
reaction, with production of a cloud of NO2, but also lots of white fumes. You may even get ignition, so be prepared!
- Turpentine (e.g. from pine trees, or some synthetic substitute, which differs from country to country) and white fuming nitric acid form a
hypergolic mix! Drip turpentine into 0.5 ml of acid. Again, be careful, it may splatter.
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chornedsnorkack
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Quote: Originally posted by woelen  | | If you have P4O10, then you can try to make N2O5 by carefully distilling that from a mix of P4O10 and HNO3. N2O5 is a solid, which sublimes at 50 C or
so and can be distilled in an all-glass apparatus. It is very reactive and allows one to make certain anhydrous nitrates, which cannot be made from
nitric acid and which cannot be dehydrated without losing HNO3 and formation of basic nitrates. Be careful though, N2O5 is rather nasty stuff and very
reactive. Know what you are doing. It can decompose very violently to NO2 and O2. |
I see the properties of N2O5 quoted as melting at +41, boiling at +47, so liquid should be observable.
Does N2O5 freely dissolve in HNO3? In the common liquid range (between +41 and +47), are the two freely miscible?
How easy to handle are concentrated solutions of N2O5 in HNO3? Like, what is the solubility at +20?
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sbreheny
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| Quote: Originally posted by woelen | For small demo-experiments, which demonstrate its properties you could do the following:
- Take 1 ml of iso-propyl alcohol (very common, easy to obtain) and drip 0.5 ml of acid in this --> this will lead to an extremely violent
reaction, with production of a cloud of NO2, but also lots of white fumes. You may even get ignition, so be prepared!
- Turpentine (e.g. from pine trees, or some synthetic substitute, which differs from country to country) and white fuming nitric acid form a
hypergolic mix! Drip turpentine into 0.5 ml of acid. Again, be careful, it may splatter.
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Furfuryl alcohol and 95+% HNO3 are a hypergolic fuel/oxidizer pair that produce a very bright flash. As you say, great care is needed (definitely eye
protection and keep the qty very small)
[Edited on 17-2-2020 by sbreheny]
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Bedlasky
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Hi.
So I recently did few simple experiments with 99% HNO3. Here is an article about it in czech and english. This time there aren't only pictures, but also videos.
[Edited on 24-2-2020 by Bedlasky]
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Sulaiman
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I like the Safety and Waste sections being highlighted at the beginning of the article.
The videos do not play for me (P7 laptop, Win10, Chrome)
Blocked by owner, only via YouTube but no link available.
CAUTION : Hobby Chemist, not Professional or even Amateur
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Bedlasky
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Videos should work now. If there will be still problem with playing, please let me know.
Safety is especially in this experiment important. A week ago few drops of 99% nitric acid spills on my finger during manipulation. After a second it
started pain like a hell. I quickly wash it and I am fine, still few yellow spots on finger, pinkish skin on place where droplets had fallen, but
thats all. Skin on hands is more durable. But I know people who have scar on hand caused by this acid. I wouldn't definitely want this acid on face or
eyes. Face protection is really needed (at least eyes protection).
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Bedlasky
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I decided to try reaction of nitric acid and n-propanol and methanol. There was no visible reaction at all in both cases. After nitric acid addition
there was only white fumes of nitric acid. With n-propanol there was one or two small "pops".
So yellow colour of ethanol after addition of nitric acid wasn't caused by nitration of ethanol, but nitration of impurities (ethanol was denaturate).
It's interesting that primary alcohols doesn't react violently with 99% HNO3, but secondary alcohols does. Sadly I don't have access to another
secondary alcohols, only to isopropyl alcohol.
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