Sciencemadness Discussion Board

Mercury pyroantimonate challenge

vano - 6-3-2021 at 06:56

Hi. I have read some things about this compound, sometimes described as red mercury, since no one knows what it really was while this compound has a red color like iodide and oxide. I do not believe it is red mercury, but I wonder how it is made. I have not found ways of its synthesis anywhere on the internet, however it is interesting that it decomposes at high temperatures, unlike other compounds of mercury.

Some info:
Formula - Hg2Sb2O7
Molecular weight -756 u
Melting point - 700°C
Density - 9.5-10.5 T / cubic meter
Also called oxystybate.

Maurice-VD-3 - 6-3-2021 at 10:01

The formula Hg2Sb2O7 is a 1:1 mixture of HgO + Hg(SbO3)2. And it can be made by mixing solutions of HgCl2 and potassium antimonate KSb(OH)6·(1/2)H2O, which can also be written KSbO3·(7/2)H2O. This product is commercial.

vano - 6-3-2021 at 11:15

Quote: Originally posted by Maurice-VD-3  
The formula Hg2Sb2O7 is a 1:1 mixture of HgO + Hg(SbO3)2. And it can be made by mixing solutions of HgCl2 and potassium antimonate KSb(OH)6·(1/2)H2O, which can also be written KSbO3·(7/2)H2O. This product is commercial.


Thanks. Where did you read about that?

[Edited on 6-3-2021 by vano]

Bedlasky - 6-3-2021 at 13:07

It is logical pathway - precipitation by mixing of solutions of soluble antimonate and soluble mercury salt. Btw. I think that correct formula for this compound is Hg[Sb(OH)6]2, because in solution antimonate exist as [Sb(OH)6]-.
Quote: Originally posted by vano  
I have not found ways of its synthesis anywhere on the internet, however it is interesting that it decomposes at high temperatures, unlike other compounds of mercury.


I don't think that heating any mercury salt is smart idea.

vano - 6-3-2021 at 13:47

Quote: Originally posted by Bedlasky  
It is logical pathway - precipitation by mixing of solutions of soluble antimonate and soluble mercury salt. Btw. I think that correct formula for this compound is Hg[Sb(OH)6]2, because in solution antimonate exist as [Sb(OH)6]-.

Quote: Originally posted by vano  
I have not found ways of its synthesis anywhere on the internet, however it is interesting that it decomposes at high temperatures, unlike other compounds of mercury.


I don't think that heating any mercury salt is smart idea.


This compound doesn't decompose. Also formula is different. Look at.
https://www.sciencedirect.com/science/article/abs/pii/S09258...
https://ru.wikipedia.org/wiki/%D0%9E%D0%BA%D1%81%D0%B8%D1%81...
(Use Google translate)

[Edited on 6-3-2021 by vano]

Bedlasky - 6-3-2021 at 14:45

But this Hg2Sb2O7 is prepared in solid state. Resulting compound can be quite different than one obtained from aqueous solution. Na[Sb(OH)6] was considered to be Na2H2Sb2O7.5H2O - this can be precipitated from aqueous K[Sb(OH)6] and Na+ salt.

[Edited on 6-3-2021 by Bedlasky]

S.C. Wack - 6-3-2021 at 19:36

Yes its the red mercury.