[MrOHBrown]

Hey there, I have made a solution of HgCl₂ (6g/100ml) and was wondering how I could reduce the Hg. Any ideas?

Hg(NO₃)₂ is a lot more soluble, do you think I should use that instead?

[sjb]

What do you mean by reduce the HgCl₂? Dilute it, or convert it into Hg⁰ or similar?

If you're looking at lowering the mercury content of your solution, one way might be to react it with aqueous ammonia to form the precipated polymer Hg(NH₂) ? (from Greenwood and Earnshaw, Chemistry of the Elements, 2nd edition, p1219-1220) ?

S

[Arkcon]

HgSO₄ (srry, should have been mercury sulfide, HgS₂) is quite easy to chemically reduce to free metal.  Simply heating it in an evacuated sealed tube is adequate.  It was, a cute demonstration, back in ancient time of low liability, but I've only read about it, I've never seen it done.  Although, I know industrially, that's how cinnabar ore is refined into mercury metal, by simply distilling the mercury free.

*[EDIT]* fix compound

[AWK]

Practically almost all reducing agents reduce Hg₂₊ to metallic Hg
eg
Hg(NO3)2 + Fe = Hg .
but HgCl2 + Fe = Hg2Cl2  . then an excess of Fe reacts very slowly to reduce Hg2Cl2 to Hg

Other common metals , eg Zn, Cu, even Pb do the same.

[MrOHBrown]

SJB, by reducing it I mean I want Mercury! You know, throw a couple of electrons it's way and have it do it's Terminator-2 thing.

Arkcon, I believe Cinnabar is HgS, I have some Cinnabar but I love it too much to mash it up and I have no HgS at school, just the Nitrate and Chloride.

AWK, I have already tried your suggestion and I have left it over night, the reason why I posted was that the copper added produced a white solid powder and Mg produced a brown percipitate... I'll let you know how they're looking this afternoon when I get home form work.

I also put a current through HgCl₂ solution using copper electrodes, now that was doing some weird things... I'll let you know how they look.

But yeah, the low solubility of Mercuric Chloride might be leaving me with very little cations to work with.

[Arkcon]

Please be careful with producing small amounts of free mercury, especially under conditions which will produce heat, like electrolysis.  If the fluid sputters or fizzes, you may be evaporating free mercury or it's solid salts.  My cinnabar trick is not even done anymore, ant that was in a sealed container, that should be enough of a hint, we don't make mercury in class anymore.

[MrOHBrown]

Trust me, I do this AFTER the kids go home.

In NSW we aren't allowed to purchase more, in any form, so I decided I'd learn a thing or two about the stuff before someone eventually throws it out.

But yes, I did pull the plug when the eletrolysis experiment was getting hot, besides, all it did was oxidise the copper electrodes and then reduce it again!