mercury(II) chloride

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I needed about 2g of HgCl2 so decided to make it from the small amount (~3g) of Hg I reclaimed from the switch of an old thermostat. I looked over the forum pretty thoroughly before deciding to use the Mr Anonymous prep presented by Polverone in another thread. What I liked about this prep is that I could do it all in one vessel (basically) with no filtration.

The Hg was dissolved in a 50 ml Erlenmeyer flask at room temperature in con HNO3 in my hood per procedure. The clear faintly green solution of Hg(NO3)2 was then placed in a small (~4") evaporating dish.

The evaporating dish was placed on a 600 ml beaker containing about 250 mL H2O as water bath heater. Per procedure the water was just barely boiling. This very slowly dried the deliquescent mercuric nitrate hydrate to a mushy white solid. In fact, it never really dried even after several hours, and IMO wasn't going to dry due to inadequate heat plus the swirling water vapor from the bath. Therefore the dish was removed from the bath and placed on a gauze supported by a ring about 3/4" above the hot plate set at medium heat (see picture below). Here the hydrate fairly quickly turned into HgO with a delicate yellow color. This powder shows no signs of deliquescence. Tommorrow this will be converted to HgCl2.



<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: added warning]

[Edited on 14.10.13 by bfesser]

HgCl2

Although this may not be the best thread I will report my preparation of HgCl2 to maintain continuity with my previous post. If a mod wishes to move one or both posts it is OK with me.

To the HgO prepared yesterday I added the 20% excess of con HCl per the procedure of Mr Anonymous. This was then placed on the 600ml beaker water bath used before. Here I was very careful to just keep the water at barely an occaisional boil bubble to minimize heat and sublimation. The liquid turned yellow and steadily evaporated away up my fume hood exhaust. The solid tended to form on the evaporating dish wall just above the liquid. This was finished after 1/2hr or so.

The fume hood was vital for this step I think. Although the vapors were mostly H2O and HCl I'm sure some HgCl2 traces were present. The middle of the upper leading edge of the lower baffle of my hood, which is bare aluminum, now has a discernable metallic mercury look to it. Not much there, but noticeable. It may have been a better idea to do this outside.

The pure white HgCl2 was easily scraped off the bottom of the dish and placed in a tared bottle. The net weight indicated a yield of 100% which is a good sign.

Would I do this again? Probably not. Seems too risky.

Although the product is hard to see as it is so white, here's a picture:

HgCl2 Synthesis (mercury (ii) chloride)

Feel free to merge this thread, I'm not sure if this has been posted before. Here is a run through on the synthesis of Mercury (ii) Chloride I've done recently.

Ill start with the HgSO4 formation:

Hg + 2 H2SO4 → Hg(SO4) + SO2 + 2 H2O

A conical flask (Erlenmeyer) equipped with a magnetic stirbar was charged with 39.56 g of Hg and ~120 mL of H2SO4 ( I used a beaker you all know how accurate these things are). Gradually heat was applied and magnetic stirring was started. Initially the solution appeared clear with beads of Hg at the bottom of the flask. A thermometer was not used in the initial reaction, once white vapors appeared the heat was turned down to minimize acid loss. The entire reaction was stirred for 18 hours to ensure all Hg had converted to HgSO4.

Here are some pictures of the process (ill post the 2nd half here soon...)

Did you use concentrated sulfuric acid (98%) or a weaker sulfuric acid like battery acid?

So how long did it take for you to dissolve the mercury?

I would like to hear and see more of your results if you can make that available.
I've wondered about mercuric compounds but was hesitant in doing what you're doing
because of the toxic nature of the substance.

thanks for sharing.

Quote: Originally posted by jamit

Did you use concentrated sulfuric acid (98%) or a weaker sulfuric acid like battery acid? So how long did it take for you to dissolve the mercury? I would like to hear and see more of your results if you can make that available. I've wondered about mercuric compounds but was hesitant in doing what you're doing because of the toxic nature of the substance. thanks for sharing.

Quote: Originally posted by peach

Be careful playing with mercury salts inside in open vessels, the chloride and nitrate (for instance) will both sublimate at rather low temperatures and be evaporating into the air prior to this. If you're breathing the vapour in, they'll dissolve fine through the lining of your lungs, straight into your bloodstream and on to your brain where each of those mercury ions will jam a neuronal growth cone (which are used to create new memory associations). [Edited on 27-7-2012 by peach]

Im really getting the mothering vibe from you peach.

Looking forward to see how this syntheses turns out, poly.........!!

Are you requiring the Mercury(ii) chloride, so that you can synthesise other Hg(II) compounds, or is it for the challenge of synthesis of the HgCl2?.......

I personally am fascinated by Hg, its so unlike other materials to be found, and some of its compounds are superb colours.

1) Adding hydroxide to mercury(II) results in the precipitation of mercury(I) oxide, when cold the precip is a brilliant yellow, which Ive found seems to cling and stain glassware readily. (its also slightly soluble in water giving a very weak alkali.
If its produced in hot/ boiling solutions, the precip is orange I think, due to larger particle size, this form is less reactive than yellow HgO. ( similar to Lead(II) oxides, litharge and massicot.)

2) Mercuric iodide, is a fantastic scarlet/ salmon colour, the original addition of the Iodide ions, gives a yellow precip, , but turns scarlet almost immediately.
If the scarlet form is dried and heated as a powder, if rapidly turns yellow, and stays yellow, when cold. An amazing change happens back over into the scarlet form ,if you gently prod the yellow, with a glass rod etc......

3) adding Al foil to HgCl2 soln, amalgamates the Al, in a strange, shimmering, quivering layer on the Al foil. It gives the illusion of the Al foil melting, and forming dense drops in the bottom of the vessel. The Hg is easily recovered by adding the amalgam to conc, HCL or NaOH, dissolving the Al out of the amalgam.

Quote: Originally posted by S.C. Wack

That method should never have been read much less followed. This will continue over and over...

Quote: Originally posted by polymerizer87

The excess H2SO4/H2O was decanted off the HgSO4, and a previously prepared 1 L dH2O HOT was poured into the Erlenmeyer flask until the HgSO4 turned bright yellow/orange (I agree with the commentary on Erowid that the addition of hot dH2O may be decomposing the HgSO4, I'm considering taking this out) The HgSO4/dH2O/residual H2SO4 solution was then filtered through a buchner funnel with a 2.5 micron filter. The bright yellow/orange filter cake was then transferred back to the flask and washed with a previously prepared 1 L saturated NaHCO3 (~80 g/1 L) solution.

Gosh. It is quite foolish to work with mercury compounds (even if it's only inorganic salts) without having invested any time in learning their chemistry. And to outdo your own laziness you haven't even bothered to search this site.

Yes, Hg(II)SO4 forms a basic sulfate with water. It's a trivial acid-base equilibrium thing: acidify by dropwise addition of H2SO4 and practically all will go in solution with some patience. This is elementary high school chemistry, if you don't even understand that, store your flasks in a safe place and start reading. The first comment on the Erowid site is silly - You're supposed to use the filtrate not the filter cake! The method is wasteful, but it is not messy (if you have some feeling about Hg chemistry). Just reuse the precipitate by dissolving it in dil. H2SO4. The second commenter doesn't seem to know much about chemistry either.

Jeez!

I remember doing something very similar. It is actually a pretty sweet way of making SO2 while you're at it

Nice Idea

@Bfesser - If he wants to practice his New Age medicine with mercury salts, let him do so and drive natural selection

Truth be told, some of my customers are New Age-y people buying my pretty Alum crystals, among other things. I don't mind them so much!

@loosejohnny - It'd be far easier to just purchase Mercury as a metal, than attempt to isolate it from ANY of it's salts. What exactly are you trying to accomplish?

loosejohnny, just dissolve it in water and add any metal lower on the scale (I forget the exact name and cant find it, can anyone help a young fool ) such as: Mg, Al, Zn, Fe, Pb, Cu or Ag.
so chuck in a few nails or pennies.
of course you will respect all safety features which you will look up before attempting this...

Quote: Originally posted by Wizzard

It'd be far easier to just purchase Mercury as a metal, than attempt to isolate it from ANY of it's salts.