LD5050
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Issue making mercuric chloride...
I found a couple thermostats and collected 5 grams of mercury metal. I followed NileRed's video on youtube to make the HgCL2.
Mercury+Nitric Acid -->Mercury (ii) Nitrate-->Mercury (ii) Oxide-->Mercuric (ii) Chloride
Now in NileRed's video after he reacts the mercury with Nitric acid it dissolves and then he evaps off the acid to leave a yellowish white powder. He
then proceeds to heat it until it obtains a very light pinkish color and then he pours in concentrated HCL and evaporates off the acid to leave a pure
white powder which he claims is pure Mercuric Chloride.
Problem: After NileRed removes the nitric acid and heats the powder until light pink color forms he moves on to convert the supposed mercury oxide
into mercuric chloride. But what he has is obviously not Mercury oxide because HgO is a bright orange red color.
So when I was replicating his procedure I continued to heat the shit out of my mercury
nitrate until it turned yellowish and when taken off the heat it turned bright orange/red.
Ok so now I have a nice orange/red powder that I think is HgO. So I proceed onto the next step. I measure out around 6ml of 31% HCL and pour it onto
the HgO, immediately the mixture sizzles and reacts and turns the HgO grayish white. I then put over heat and evap off the HCL and I am now left with
a brown dry powder.
What is going on here? Why arn't I left with nice white Mercuric Chloride? Did I not add enough HCL to react enough with the HgO? Did I add too much
and it over reacted? Also I should say that I was pretty careful with the heat when evaporating off the HCL so I don't think that I burnt it but maybe
this is still a possibility?
Any suggestions or tips on how to correctly make Mercuric Chloride would be appreciated. I have about 2.5 grams of mercury left and I really need some
Mercuric Chloride. PLEASE HELP!
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Sidmadra
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Just speculating since I don't know this reaction, but maybe the brown powder is a mixture of HgO and HgCl2, the brown color resulting from a mix of
the orange and white.
Also a word of warning, I would advise against purchasing HgCl2 online if you are a hobbyist, if you are in the USA. I won't go into much detail here
but a purchase of it online caused me to have a fairly unpleasant encounter with the police.
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laserlisa
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Sorry but this wont answer your question, but if I understand correctly mercury wont react with aq HCl directly?
What if you add hydrogen peroxide to the HCl, wont the mercury dissolve then?
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Amos
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If you can get all of your supposed mercuric oxide to dissolve in concentrated hydrochloric acid, I'd advise using as little acid as possible and
simply evaporating the solution down at room temperature for a few days. You should get some nice pretty crystals of mercuric chloride free of any
impurities that might be giving you nasty coloration.
You said you only have 2.5g left. I sincerely hope you didn't nonchalantly dispose of mercury compounds somewhere like the garbage or sink just
because you were frustrated with the results.
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Amos
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Additionally, Nile Red may not have obtained mercuric oxide by heating the nitrate solution to dryness, but you don't need to; boiling mercuric
nitrate with excess hydrochloric acid drives off the nitrate as nitric acid and leaves you with mercuric chloride anyway.
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fluorescence
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I don't really like Nile's method either.
Honestly speaking, there are a couple of elements where I have no clue how to make clean salts. Take Arsenic for example, Arsenous-, Arsenic acid and
their oxides. If you check in books, wikipedia the net there are different answers to what actually forms when. Sometimes heat can make a difference,
too and I don't really like to have a mixture of different oxidation states.
For Hg it's pretty mucht the same. As long as you have the Nitrate there are two options what you can have, HgNO3 and Hg(NO3)2. You can use
a huge excess of HNO3 to convert even more but I suggest you take samples and titrate them with a chloride or HCl. Hg(I) will precipitate while Hg(II)
doesn't. And this is the only step where you can really check that because later as you said you will add HCl and it will turn out all messy because
of the mixed oxidation states. So I guess the only option would be to wait and heat till no test sample shows a precipitation anymore and then
continue so its all Hg(II).
This was how I originally planed the experiment. I have to say I never tested it that way and I have no clue if this yields better results but I would
try to really get only Hg(II) in the very first step since this is the one where you can still save it somehow and then proceed with the rest.
Edit: Nevermind, I just saw that Hg(I)oxide will decompose at higher temperatures...
[Edited on 6-3-2017 by fluorescence]
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joluvschemistry
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dude, bubble pure chlorine gas into a round bottom with elemental mercury. its good to swirl the flask but you can let it puddle. itll harden, turn
like gray I think and you just scrape it out. its not very hard.
I just dripped hcl into an Erlenmeyer with a small amount of calcium hypochlorite, the smoke is green and horrible, wear a gas mask! I did it w/o one
outside holding my breathe during the swirling.
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Melgar
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Or avoid bubbling Cl2 (tends to rust everything in the room if you're not careful, and if you're bubbling anything that reactive into a container with
Hg in it, you probably aren't.) altogether, and just put the Hg in HCl, and add H2O2 slowly to generate the Cl2 and thus HgCl2 in situ. You
will likely get HgO too, but any HCl in solution should make quick work of that.
[Edited on 3/9/17 by Melgar]
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