postart
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HgCl2 from cinnabar
I was looking into methods for producing mercury salts that can be used in reductions when I came across "Cinnabar" which is HgS. I was thinking
adding some HCl would yeild mercuric chloride, does this sound correct? A one pot shot to HgCl2 would be pretty cool. If not what about using H2SO4
first like when using elemental mercury.
HgS + 2HCl ---> HgCl2 + H2S
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Jor
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I'm not sure but black mercuric sulfide is hardly attacked by concentrated hydrochloric acid, only by strong oxidising acids such as aqua regia.
However, cinnabar is the red form, so this may not apply to cinnabar. Anyway, I think heating with concentrated nitric acid or aqua regia will work,
giving a precitipate of mercuric sulphate, wich redissolves upon diluting. Then precitipate HgO from this and redissolven in HCl.
However, you could also try dissolving in HCl.
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madscientist
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Dissolve it in an acid that yields a soluble salt, such as nitric acid or acetic acid. Isolate that salt, mix with sodium chloride solution, and
filter the HgCl2 precipitate.
Use appropriate ventilation! H2S will be liberated on contact with these acids. It doesn't just stink, it's deadly, every bit as much so as hydrogen
cyanide gas! And if the smell goes away, it's not necessarily gone. Higher concentrations, or extended exposure, will kill your sense of smell.
[Edited on 20-10-2010 by madscientist]
I weep at the sight of flaming acetic anhydride.
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not_important
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Jor has it - HgS doesn't dissolve at any speed in most acids, even hot HNO3 can be slow. Aqua regia is both oxidising and complex (Cl-) forming.
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Lambda-Eyde
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Quote: Originally posted by madscientist  | Dissolve it in an acid that yields a soluble salt, such as nitric acid or acetic acid. Isolate that salt, mix with sodium chloride solution, and
filter the HgCl2 precipitate.
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Mercury(II) chloride HgCl<sub>2</sub> is perfectly soluble in water - 7,4 g per 100 ml. Mercury(I) chloride, HgCl, is not.
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postart
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Being that HgCl2 is an expensive chemical I was wondering if it would be possible for one to synthesize, get a lot anaylasis, then sell to companies
or hobby chemists?
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Magpie
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The industrial method for obtaining mercury from cinnabar is by heating it in a current of air thereby distilling off the mercury. Doing that on a
laboratory scale might be a challenge.
Once you have the mercury you can get HgCl2 as shown here:
http://www.sciencemadness.org/talk/viewthread.php?tid=3842#p...
[Edited on 20-10-2010 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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madscientist
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HgCl2 is significantly less soluble than Hg(NO3)2; I used to prepare HgCl2 by mixing saturated solutions of Hg(NO3)2 and NaCl and filtering the
precipitate. Guess using NaBr might be better, HgBr2 is much less soluble than HgCl2.
Didn't realize cinnabar was that unreactive. Scratch the nitric acid/acetic acid idea.
I weep at the sight of flaming acetic anhydride.
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mr.crow
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You can make HgI2 which is insoluble and very pretty looking (from woelen's page). The only problem is the left over nitric acid might oxidize the
iodide
Mercury compounds still scare the crap out of me. I wouldn't trust myself to not contaminate everything. No way you would be allowed to manufacture
and sell it yourself.
Since HgS is basically inert you can use this to clean up mercury waste! Just use sodium sulfide or polysulfide
Double, double toil and trouble; Fire burn, and caldron bubble
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postart
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Found this procedure at another forum:
Experimental:
Read before you try!
This reaction generates very toxic and nasty NOCl, NO and chlorine gas fumes, so you should go outside!
Pour 567ml HCl, 33% (d = 1.17, 6 mol) in a 2000ml pyrex beaker. Then pour in 698g cinnabar (HgS, 3 mol) and swirl around a few times. Now quickly add
183ml HNO3, 53% (d = 1,3, 2 mol) in one portion, swirl a litte and make a few steps back, because the reaction will begin quickly (depending on temp.)
Don`t breath the fumes!
Literature says that auqa regia is formed in about 15 minutes, but in SWINM´s case the violent rxn begun after 30 sec....
There were lots of brown-yellow fumes of NOCl, NO (wich forms brown NO2 on air) and Cl, and elemenar Sulfur was formed swimming at the top. After a
few minutes the rxn subsides, leaving a clear-yellow liqud with collodial Sulfur and maybe some unreacted red HgS depending of the conc. of the used
acids. You can filter of this with the sulfur, or you can add more HCl/HNO3 in small portions (caution fuming!!)
Wait until the rxn cools down and no more toxic fumes envolve. Then filter of the Sulfur with vac at home.
Now you have an acidic sol. of about 800g HgCl2 in about 0.5 liter H2O with some HCl and HNO3.
If you want to evaporate this sol. at normal pressure, more fumes are envolved and the heavy HgCl2 will beginn to sublime.
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mr.crow
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Why does it make elemental sulfur? Won't it oxidize to sulfite or sulfate?
That sounds like suicide. If you want to do this procedure here is my advice:
Let the solution cool and offgas, we don't want any chlorine. Maybe bubble air through it (watch out for splatter!!!).
Add a small amount of NaOH solution to neutralize the acid. When the acid is gone it will produce solid mercury oxide. Stop when this happens and
filter it off and add to the waste.
Now add a solution of NaBr (found at wal-mart). This will precipitate HgBr2 (0.5g/100mL). This chemical is just as reactive.
The waste liquid and filter papers will be highly contaminated. Put it all into a jug and pour in some sodium polysulfide from the photography store.
Watch out for H2S.
Have fun?
Double, double toil and trouble; Fire burn, and caldron bubble
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The WiZard is In
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| Quote: Originally posted by postart | I was looking into methods for producing mercury salts that can be used in reductions when I came across "Cinnabar" which is HgS. I was thinking
adding some HCl would yeild mercuric chloride, does this sound correct? A one pot shot to HgCl2 would be pretty cool. If not what about using H2SO4
first like when using elemental mercury.
HgS + 2HCl ---> HgCl2 + H2S |
Me the analogue guy again. When I have a question like this
id often turns to Mellor's 16-volume plus supplements opus. Vol. 4
p. 952 notes among other things....
... burns in chlorine with incandescence forming sulphur chloride and mercuric chloride.
when boiled with a mixture which develops chlorine—say,
manganese dioxide or antimonic or arsenic oxide and hydrochloric
acid—mercuric chloride and sulphur are formed.
when treated with in aqua regia, it dissolves quantitatively as
mercuric chloride—only a little sulphuric acid is formed.
djh
----
Many scientist, most notable Carl
Sagan, have believed the sheer
number of environments in the
universe makes it possible that life
had developed elsewhere. But as
Clancy points out, "It's one thing to
believe that life might exist on other
planets, and quite another to believe
that it is secretly examining your
private parts."
Stuart Vyse's review of :—
Susan A Clancy's
Abducted : How People Come to Believe
They Were Kidnapped By Aliens
Science 310 [5752] 1280-81
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