Vlad
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Preparation of Na metal using a Hg cathode
I picked this up on another list:
For those of you wishing to produce small amounts of sodium metal, the
following is a procedure that will do so.
Using NaCl in water as an electrolyte and a carbon rod or stainless steel as
an anode, prepare a mercury cathode by placing mercury in a suitable
container and inserting an insulated wire into it so that the exposed wire
end is covered by the Hg. Na from the NaCl will be plated into the Hg and
considerable amounts can be prepared this way. As long as the current is
flowing the Na will stay in the Hg but when the current is turned off it
will start to form NaOH.
The sodium amalgam can be removed from the electrolyte, dried and keep under
kerosene to preserve the Na. Since Hg has a much lower boiling point than Na
it may be selectively distilled off leaving the Sodium metal behind in the
retort.
WARNING: Do not even think of doing this at home if you have no experience
handling these metals. Permanent injury can result.
[Edited on 22-2-2006 by Vlad]
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garage chemist
chemical wizard
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Funny that I just thought of giving this a try a short time ago.
For the electrolyte, using a NaOH or maybe Na2CO3 solution might be a better idea than NaCl, since no chlorine will dissolve into the electrolyte and
cause the formation of HgCl2 at the cathode (in very small amounts, but due to the high toxicity one must be aware of this).
Sodium amalgam is a useful reagent in organic chemistry, capable of doing interesting and unexpected reactions, like turning cinnamic acid into
dihydrocinnamic acid.
The disadvantage is that several hundred grams of mercury are needed to be able to perform such reactions.
But the mercury can be "recharged" easily as often as wished.
See also here (scroll down): http://webpages.charter.net/kwilliams00/bcftp/docs/mercury.h...
In order to obtain Hg- free metallic sodium, the Hg could be distilled off in a bent test tube, the same design that I use to reclaim Hg metal from
old dental amalgams.
I'll make a topic about this distillation method soon. It's really useful for distillation of extremely high- boiling substances.
OT: I noticed that United Nuclear has sodium metal for sale, in large chunks under kerosene. This might be a chance for those living in the US!
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S.C. Wack
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% Na in industrial process amalgam: 0.25-0.5%
Solubility of Na in Hg at STP: 0.6%.
Might as well open a mercury recycle refinery as well. Just kidding! Imagine going to the city/county/state for permits for such a thing as Joe Blow,
Inc.
"But no one will sell me liability insurance. How much will I need for you to approve self-insurance?"
[Edited on 23-2-2006 by S.C. Wack]
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garage chemist
chemical wizard
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Just look at my latest posting in the dental amalgams thread. It shows how to distill mercury with very simple equipment.
Also, the 0,6% solubility of Na in Hg applies for the liquid amalgam. Hg can absorb a lot more sodium, the amalgam just turns into a butter- like mass
during this, which melts a bit above room temperature.
2-3% sodium content is easily realized.
Kneading the buttery amalgam from time to time under the electrolyte to expose fresh surface for sodium absorption would be ideal.
And 100g mercury have got a volume of only 7,4 ml.
2-3 g of sodium by distilling 7,4ml of mercury from an amalgam sounds like a much better yield, doesn't it?
[Edited on 23-2-2006 by garage chemist]
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BromicAcid
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Here is a PDF I downloaded quite some time ago (from the ACS website I believe) regarding the prepartion of the alkali metal amalgams.
Attachment: alkalimetalamalgams.pdf (566kB)
This file has been downloaded 1012 times
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garage chemist
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Ah, great, thanks Bromic! Where do you always find that stuff?
What is the ACS website?
So 1,5% sodium is obtained in the solid amalgam. That's still very good.
For me, applying this process to potassium amalgam would be the most interesting thing.
I can easily buy sodium, but not potassium, and even if I could it would be expensive as hell.
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BromicAcid
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The ACS is the American Chemical Society at http://www.acs.org/ I think you can view the first page of any of their articles if you are not a member, in references it appears as JACS or the
Journal of the American Chemical Society. But they have lots of other journals there too like the Journal of Organic Chemistry and such.
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S.C. Wack
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I believe that the proper abbreviation is J. Am. Chem. Soc., which I never use but most journals do. The above, for the record, is 31, 799 (1909).
I say that because on looking I see that I also have the earlier article mentioned, 29, 321 (1907), so here it is FWIW. It uses the method of J. Phys.
Chem. 7, 29 (1903) which I got from Gallica. The two are combined here:
Attachment: electroamalgam.pdf (350kB)
This file has been downloaded 795 times
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evil_lurker
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Fun as sodium metal production is, if you need it UnitedNuclear.com is now selling it.
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