Arrheniusthegreat
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When dissolving Hg in HNO3...
I'm looking to prepare mercuric nitrate. In process, when mercury is added to the nitric acid, it produces Hg vapors, especially if my soln heats up
too much. I have an idea to make use of the vapors produced by creating a trap of sorts to recover the vapors. So say for instance, I have a glass
bath, I add to the bath approximately 75ml or however much to fill a half inch up or so of nitric acid. Then I place a flat bottom flask in the bath
into the small pool of nitric acid. The flat bottom flask is charged with 15~20ml(in slight molar excess of about 12 millilters)HNO3. Then added is
12.5 grams Hg. So thus the Process begins. What I'm wondering is, since Hg is soluble in HNO3 could I then place a beaker over the flat bottom flask
while its dissolving so that any vapors would be absorbed into the pool of nitric acid in the bath? I know there will also be nitrogen oxides
produced. I am aware of the safety precautions and am making preparations accordingly. I hope I've made it clear what I'm talking about. Thanks,
Arrhenius.
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gsd
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No. You have not made yourself clear. Atleast not to me. Even though it involves Mercury & concentrated Nitric acid, this is a simple procedure if
you take proper precautions (Fume hood, gloves, goggles etc. Etc - the usual stuff)
1) Take Hg in a flat bottom flask which is fitted with reflux condenser.
2) Add water to cover Hg.
3) Add large excess of concentrated HNO3.
4) Provide a trap for NOx vapours.
5) The reactions proceeds on its own, however you will have to boil it at end to finish it.
Don't bother about Hg vapours escaping. Vapour pressure of Hg even at 100 deg C is not very high to escape from this aparatus - they will either react
with NOx or condense in the reflux condenser.
Gsd
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Arrheniusthegreat
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Thank you, for not making myself very clear you certainly answered my question. You offered the better alternative. So how then can I trap the NOx
fumes?
Edit: also should I run water through the jacket?
[Edited on 10-1-2013 by Arrheniusthegreat]
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gsd
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1) You must run water thru' condenser jacket.
2) For simple vapour (NOx) trap refer to Vogel or any other std. Preparative chemistry book.
Gsd
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Arrheniusthegreat
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Thanks, I appreciate it.
The clearest way into the Universe is through a forest wilderness. - John Muir
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woelen
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In this reaction you have to worry about mercury, dispersed into the air. No mercury vapor, but the reaction is quite vigorous, especially in
the beginning and then small droplets of solution are ejected from the liquid by all the bubbles of gas. These small droplets contain mercury ions.
The NOx vapors and small traces of HNO3 can be an immediate problem, you definitely should avoid inhaling these, but these vapors quickly disappear,
especially if you have good ventilation. Mercury salts, dissolved in small droplets, however, do not disappear. These can contaminate your house and
cause long term low level exposure to mercury salts. I personally see more problems with this than with the NOx vapors. The latter are clearly visible
and smellable and once they are gone, you know they are gone. But what about the small amounts of mercury salts which are scattered throughout the
house? Droplets into the air, the HNO3 and water evaporate, the solid mercury salt remains behind as a tiny dust particle and settles on the floor, on
furniture, carpets, whatever may be present in the room and you won't notice any of this.
So, you need to make a very good scrubber for the vapors and nothing may escape into the air. If you cannot assure this, then do the experiment
outside on a breezy day. Even there, use a scrubber, but if some of the vapors escape, the harm is less severe.
Just to get an idea of how many droplets actually escape into the air, take a glass of coca cola and keep your finger a cm above the surface. You feel
many cold droplets of liquid at your finger. A much better demo actually is to take some acid (e.g. vinegar or very dilute HCl, something like 5% or
so) and add a spatula full of sodium bicarbonate and keep your finger above the liquid and foam. You will be surprised to feel how much of the liquid
escapes into the air. This also happens with your HNO3, containing Hg-salts.
[Edited on 10-1-13 by woelen]
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Arrheniusthegreat
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Thanks woelen, I have to ask though, as to how any particles may escape when done in a 250ml flat bottom flask setup with a condensor with ice cold
water. As well as attached to the top is a vacuum adapter to which is connected a tube via stopper that is led into my scrubber? Would that contain
these vigorously foaming particles of mercury salts?
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Oscilllator
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Quote: Originally posted by Arrheniusthegreat  | | Thanks woelen, I have to ask though, as to how any particles may escape when done in a 250ml flat bottom flask setup with a condensor with ice cold
water. As well as attached to the top is a vacuum adapter to which is connected a tube via stopper that is led into my scrubber? Would that contain
these vigorously foaming particles of mercury salts? |
I would not contain very much, if any mercury salts. But it is never a good idea to take chances with heavy metals like mercury
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Arrheniusthegreat
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How the hell would they splash all the way up my freezing condenser into the tube, all the way THROUGH the tube, out the tube, through the scrubber
and back out? Sounds like a bunch of scrutiny towards the ideology of creating a mercury salt as opposed to any of the logic I've presented in my
setup. Show me viable evidence that mercury salt vapor would get out.
The clearest way into the Universe is through a forest wilderness. - John Muir
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Arrheniusthegreat
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The scrubber may not stop the salts, but the apparatus will. If you're disagreeing please show what proof and reasoning you have to do so.
The clearest way into the Universe is through a forest wilderness. - John Muir
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woelen
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Accidents can happen always. The apparatus may have leaks, something may get loose and gas may escape. But I have to admit, if you have a setup, which
contains all the gas and scrubs it, then virtually no Hg will escape the system.
My post was especially directed to people who dissolve mercury in a beaker or erlenmeyer filled with some HNO3 and just let the gas escape into the
air. With something like copper you can do that (provided that the nitrous vaors are not inhaled of course), but with mercury you should never do
that! Not everybody uses such a setup as you describe.
Even with a setup like you describe I would not do this in a normal household setting. I still would do this outside, simply because of the risk of
leakage.
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Endimion17
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Mercury vapor is really something you shouldn't worry about when dissolving it in nitric acid. The amounts are pathetic. Recovering the vapors? LOL
If you think there's enough mercury in that vapor that it can be recovered, then you shouldn't work with mercury in the first place because
you obviously don't know enough about it.
On the other hand, soluble mercury salt aerosol is a huge deal. It's highly dangerous.
It's in oxidized state, soluble, and it reaches your respiratory system and nervous system (olfactory nerve). Combo disaster.
Aerosol also creeps out and deposits on the working surface, leaving a film of tiny crystals ready to be picked up by your hands and clothes. If it
was radioactive, a Geiger counter would go nuts close to you.
When dried, the film is dusty and can be inhaled.
If you're making lots of the metal at once (more than few drops), use double latex gloves, fume hood and cold water reflux with top equipped with
drying tube packed with mixture of sand+NaOH, secured with glass wool plugs on both sides.
Otherwise, if it's just a drop of mercury in a test tube, do it outside.
12.5 grams of mercury is almost one mililitre. That's a lot of mercury. After you're finished, consider taking a bucket of water and a sponge to sweep
your working surface.
Why do you need so much mercury(II) nitrate?
I love mercury, it's one of my favorite elements, but I'm afraid of it. It's capable of destroying the essence of who I am. That's scarier than any
burn or blasted finger.
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Arrheniusthegreat
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Damn, well. The thing is, I worked a 7 hour shift yesterday going from dissolving the mercury into nitric acid, to mercuric chloride following a guide
here on SM. it's Mr. A I believe? Or something along those lines. The only part that was done indoors, was done in a lab that was sealed off from the
rest of the house. However the nitrate was decomposed indoors with remarkable ventilation. I have a certain entire part of the lab rigged to an
overhead hood. However please, tell me more of these aerosols? I wasn't looking to recover the vapors but merely stop them. So that they could be
disposed of properly.
The clearest way into the Universe is through a forest wilderness. - John Muir
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Arrheniusthegreat
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What was done indoors was in the apparatus as I had described above.
Edit: As well as my entire work space has been cleaned.
[Edited on 11-1-2013 by Arrheniusthegreat]
The clearest way into the Universe is through a forest wilderness. - John Muir
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