Sciencemadness Discussion Board

getting mercury salts out of vacuum glassware

chemrox - 22-1-2010 at 16:50

I want to clean a McLeod Gauge of Hg oxide or chloride (not sure which). It's a white residue from once distilled Hg exposed to halide and mineral acid vapors. I'm thinking nitric would work best but am not sure.

Thanks,
CRX

bahamuth - 22-1-2010 at 17:17

Would suggest, if disposal of the mercurial waste is no problem to clean it with aqua regia, takes care of most if not all metal contaminants on glass. If any problem to remove white residue, heat it a little, ~50C.

smuv - 24-1-2010 at 08:35

Please post how everything works out. I have the exact same problem.

chemrox - 27-1-2010 at 18:02

OK-I'm going to start with nitiric and if that doesn't do it I'll try aqua regia. The problem is we got some shitty Hg.

chemrox - 16-2-2010 at 23:34

Nitric seems to be working. The residue was white. Now the 70% HNO3 is colored green and there is some metalic Hg back in the lines where there had been some white material. I initially suspected HgCl. Would HNO3 reduce HgCl to Hg and release Cl2? It's still in process. Sonification speeded things up for awhile but it was time to come home and go to bed!

unionised - 17-2-2010 at 12:42

Just for the record, I2/ KI solution also works.
Might be handy for those whose stocks of HNO3 are limited.

Jor - 17-2-2010 at 13:34

Quote: Originally posted by chemrox  
Nitric seems to be working. The residue was white. Now the 70% HNO3 is colored green and there is some metalic Hg back in the lines where there had been some white material. I initially suspected HgCl. Would HNO3 reduce HgCl to Hg and release Cl2? It's still in process. Sonification speeded things up for awhile but it was time to come home and go to bed!

No why would nitric acid reduce Hg2Cl2 to metallic Hg and Cl2? If it would oxidise the chloride, it would form chlorine and mercurous nitrate, but it will oxidise the Hg(I) instead to Hg(II).