Sciencemadness Discussion Board

red mercury compound

Jor - 25-4-2010 at 06:19

I attempted the beating mercury heart reaction yesterday.
In an Pyrex evaporating dish, I dissolved 2 small spatulas of potassium dichromate in about 25-30mL of 2M sulfuric acid.

To this I added about 0,5mL mercury. The mercury was dirty, it had some greyish layer of contaminants on it, so it didn't form single drops easy, as mercury usually does. I don't know why it's dirty, i opened a mercury switch containing 1mL of very pure mercury, and it has been stored in a plastic vial since half a year now.
Anyways I touched it with a glass pipette and with an iron needle and it didn't beat at all. I have read on some intternet pages conc. H2SO4 should be used, but some other sources use dilute acid?

Anyway, this was not my problem. Next day I returned to the experiment, and saw this red precitipate on the many mercury blobs. So I'm not sure what this is.
I think it would probably either be mercurous (di)chromate or mercuric (di)chromate (although most dichromate are quite soluble). But the strange thing is, the solution above the metal and precitipate is almost just as orange as before, while I expected a greenish/grey color, or at least a dirty brown color. It seems there is almost no Cr(III), meaning almost no mercury is oxidised. I can imagine that some of the grey material on the mercury (HgO, covered with some mercury making it grey?), reacted with the dichromate, but still i find the amount of precitipate on the mercury quite large, compared to the amount of grey material.
Now what would this compound be. I looked up mercuric dichromate, and this red. But I am not sure if this wouldn't react with mercury forming Hg(I) ?
Hehe, now I'm left with quite a mess to clean up :) Would have been much smarter to do this on a smaller scale.

[Edited on 25-4-2010 by Jor]

The WiZard is In - 25-4-2010 at 18:16

Quote: Originally posted by Jor  
I attempted the beating mercury heart reaction yesterday.
In an Pyrex evaporating dish, I dissolved 2 small spatulas of potassium dichromate in about 25-30mL of 2M sulfuric acid.



I hope you haven't created the famous super-duper just short
of nuclear, explosive Red Mercury.