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Magpie
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See this thread: http://www.sciencemadness.org/talk/viewthread.php?tid=4777&a...
If you have any questions I'll be glad to try and answer them. But please ask them in that thread. (This thread is for batteries  .)
The single most important condition for a successful synthesis is good mixing - Nicodem
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vulture
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| Quote: |
Air oxidation releasing a little I2 ? |
Washing with KI could easily prove/disprove this hypothesis.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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dapper
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sorry to dig up old (very cool) threads
just wanted to mention a source of real vermillion HgS artists pigments
http://www.greenandstone.com/v2/p/PAC.php?c=11
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UnintentionalChaos
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| Quote: | Originally posted by vulture
| Quote: |
Air oxidation releasing a little I2 ? |
Washing with KI could easily prove/disprove this hypothesis. |
Or with a little heptane (or similar hydrocarbon), which'll take on a purple tint if it is I2. DCM, Chloroform, and tet would probably also work, but
no need to bring chlorine containing compounds anywhere near the iodide just in case.
Also, where do you see real vermillion paints dapper? I can't seem to find it. I know a lot of companies do sell "vermillion" paints which are not
vermillion at all. At any rate, I have some old tubes of Winsor and Newton real vermillion oil paint...maybe 30 years old. In lead tubes no
less...still unopened and usable. The paint is probably worth quite a bit more than the mercury I could possibly extract from it.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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JohnWW
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What substitutes for HgS could they use in "vermilion" artists' paints? I would think either ZnCrO4, PbCrO4, Pb3O4, or bright red azo dyes (e.g. Para
Red, Methyl Red, Congo Red). Anhydrous finely divided hematite, Fe2O3, may also do, but may be the wrong shade of red.
[Edited on 9-7-08 by JohnWW]
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not_important
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| Quote: | Originally posted by UnintentionalChaos
Also, where do you see real vermillion paints dapper? I can't seem to find it. I know a lot of companies do sell "vermillion" paints which are not
vermillion at all.... |
http://naturalpigments.com/detail.asp?PRODUCT_ID=450-15S&...
Complete with "WARNING! CONTAINS MERCURIC SULFIDE."
http://www.iconofile.com/storefront.asp?page=Cinnabar
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UnintentionalChaos
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Oh sorry...nevermind 
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Panache
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I just purchased a litre of 10% Cadmium Sulphate solution (plus a blue dye i assume as its light blue) sold as a car conditioner. I remembered this
thread thats why i bought it but there's nothing to do with cadium sulfate now that i reread it, although one can electroplate with the solution
apparently.
Oh well no bother, i'll cleanup the solution into the salt and make it part of the collection. Interestingly the bottle has a poisons warning on it
but i can't seem to find Cd dangers other than the carcinogenic ones, does anyone know any of it's acute toxicities?
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not_important
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searched using cadmium toxicity acute
http://www.atsdr.cdc.gov/csem/cadmium/cdacute_effects.html
parent page : http://www.atsdr.cdc.gov/csem/cadmium/cdacute_effects.html
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Panache
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omg there's a disease called 'metal fume fever'.
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blogfast25
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Wanting "to do something" with Cadmium, I stumbled onto this excellent thread, so if no one minds I'll revive it.
Firstly I want to comment on Magpie's excellent method of separating Cd2+ and Ni2+, by means of sulfide solubility difference, by putting a bit of
math beef on these bones.
The solubility constants for CdS and NiS respectively are 8.0 x E-27 and 3.0 x E-19.
The acid dissociation constants for H2S are:
[H3O+]x[HS-]/[H2S] = 1 x E-7 (K1)
and [H3O+]x[S2-]/[HS-] = 6.4 x E-16 (K2)
From this page http://www.telusplanet.net/public/jcarroll/ION.HTM can be gleaned that the solubility of H2S in water is about 0.1 M, remarkably independent of pH
(apart of course for very high pHs).
Magpie adjusted the solution to 0.3 M HCl, thus [H3O+] ≈ 0.3 M.
Since as the dissociation of H2S in acid conditions is completely negligible, both [H2S] ≈ 0.1 M and [H3O+] ≈ 0.3 M are very good
approximations.
Now isolate [HS-] from K1 and insert it in into K2, then isolate for [S2-]:
[S2-] ≈ K1 x K2 x ([H2S] / [H3O+]^2)
or in Magpie's conditions, [S2-] ≈ K1 x K2 = 6 x E-23 (pretty low, huh!)
Assume for argument's sake that prior to saturation with H2S, [Cd2+] ≈ [Ni2+] ≈ 0.1 M, then it's clear that [Cd2+]x[S2-] far exceeds the
solubility constant of 8.0 x E-27 (by a factor of about 10,000) but that [Ni2+]x[S2-] is much lower than the solubility constant of 3.0 E-19 (by about
the same factor of 10,000). The separation of Cd and Ni by this method must thus be very near complete.
I'm guessing (w/o peeking) that Cu2+ would precipitate with Cd2+ but not for instance ZnS.
I'm hoping in the next few weeks to make some high purity Cadmium metal by electrolysis of molten anhydrous CdCl2. I haven't decided to start from
spent batteries or from commercial CdS yet...
[Edited on 29-7-2009 by blogfast25]
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UnintentionalChaos
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Quote: Originally posted by blogfast25  | Wanting "to do something" with Cadmium, I stumbled onto this excellent thread, so if no one minds I'll revive it.
Firstly I want to comment on Magpie's excellent method of separating Cd2+ and Ni2+, by means of sulfide solubility difference, by putting a bit of
math beef on these bones.
The solubility constants for CdS and NiS respectively are 8.0 x E-27 and 3.0 x E-19.
The acid dissociation constants for H2S are:
[H3O+]x[HS-]/[H2S] = 1 x E-7 (K1)
and [H3O+]x[S2-]/[HS-] = 6.4 x E-16 (K2)
From this page http://www.telusplanet.net/public/jcarroll/ION.HTM can be gleaned that the solubility of H2S in water is about 0.1 M, remarkably independent of pH
(apart of course for very high pHs).
Magpie adjusted the solution to 0.3 M HCl, thus [H3O+] ≈ 0.3 M.
Since as the dissociation of H2S in acid conditions is completely negligible, both [H2S] ≈ 0.1 M and [H3O+] ≈ 0.3 M are very good
approximations.
Now isolate [HS-] from K1 and insert it in into K2, then isolate for [S2-]:
[S2-] ≈ K1 x K2 x ([H2S] / [H3O+]^2)
or in Magpie's conditions, [S2-] ≈ K1 x K2 = 6 x E-23 (pretty low, huh!)
Assume for argument's sake that prior to saturation with H2S, [Cd2+] ≈ [Ni2+] ≈ 0.1 M, then it's clear that [Cd2+]x[S2-] far exceeds the
solubility constant of 8.0 x E-27 (by a factor of about 10,000) but that [Ni2+]x[S2-] is much lower than the solubility constant of 3.0 E-19 (by about
the same factor of 10,000). The separation of Cd and Ni by this method must thus be very near complete.
I'm guessing (w/o peeking) that Cu2+ would precipitate with Cd2+ but not for instance ZnS.
I'm hoping in the next few weeks to make some high purity Cadmium metal by electrolysis of molten anhydrous CdCl2. I haven't decided to start from
spent batteries or from commercial CdS yet...
[Edited on 29-7-2009 by blogfast25] |
I hope that you have extremely good ventilation. Molten metal chlorides may not be as volatile as your everyday solvents, but they do vaporize and
especially with something as nasty as CdCl2, I wouldn't want to be around them much.
Is this a project for the sake of a project, or do you need the Cd for something? If the latter, I advise you simply purchase some, as it only costs
about $10-$15 US per pound (99.9%) and is significantly less hazardous.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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blogfast25
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Few things are more satisfactory than a piece of homemade element, if possible from scraps lying around the house, as a 'backyard project', IMHO. And
this method should yield nice, fused lump metal.
I applied the same method to produce some high purity lead, using a closed electrolytic cell to siphon off the chlorine, over 30 years ago.
With such a closed cell for CdCl2, the main danger is overheating it, as the boiling point of Cadmium is a mere 767°C (lead = 1749°C). Running the
cell temperature close to the melting point of the CdCl2 (564°C) will be necessary to keep vapour pressure of the liquid Cadmium low.
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not_important
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At that temperature the vapour pressure of CdCl2 is around 10 mm Hg, and that of elemental cadmium around 40 mm.
I'd go for aqueous electrolytic, unless you feel real good about how closed the closed cell is.
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blogfast25
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Very interesting... how did you work those numbers out? The vapour pressure of various molten salts is of interest to me for another project...
In particular the relationship between pressure and temperature of a molten but pressurised salt is what I'm looking for. That is the liquid-vapour
two phase part of a (p, V, T) diagram.
[Edited on 30-7-2009 by blogfast25]
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not_important
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From scanned-in tables, may have been from CRC which has boiling points of a number of organic and inorganic substances at several pressures.
For what you're looking for, if no one here can suggest a starting point, you'll need good Google-fu to get a smallish number of candidate
publications. For pressurised cases I suspect nuclear energy research is likely the best resource.
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wg48
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metal fume fever'
I was surprised too. I had been playing with a tig welder (actually a modified plasma cutter). I used some Zinc plated steel to practice, but did
not bother to remove the zinc as per the usual suggestions/warnings for welding Zinc plated steel. I assumed Zinc being relatively harmless compared
to say lead or cadmium I did not need to be concerned. I did notice the white fumes of zinc oxide given off by the steel even after the welding as
the steel cooled down.
I developed what I assumed was flu, shivering and feeling lousy a few hours after the welding. I thought it was odd that it happened after welding
the zinc plated steel. With a web search I discovered metal fume fever. So that was probably the cause of my shivering and feeling lousy.
Apparently the fever is caused by a reaction in your lungs to the zinc/oxide dust at levels much below that which would normally be considered
poisonous.
I am much more careful now not to inhale any fumes from welding zinc or none zinc plated or anything.
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