neodymiumsulfate
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Aminocomplex of gold?
i want to recycle gold from old cpu s. i dissolved them in aqua regia, so i have in the solution gold, silver, copper and iron.
how can i separate the copper?
if i add cc ammonia solution the copper will form a complex and gold hydroxide will precipitate. does the cc ammonia dissolve gold hydroxide?
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Boffis
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Aqua regia tends to leave a lot of silver in the residue because AgCl is highly insoluble. Any gold and silver in the aqua regia can be precipitated
after dilution onto copper wire from which they can be separate by simply stirring the wire in fresh water (they often drop off spontaneously) and the
remaining liquor discarded. Any silver in the original insoluble residue can be leached with ammonia solution and then precipitated onto copper wire
in the same way. This is the way I recover Ag and Au from my lab residues.
Au3+ compounds react with aqueous ammonia to give an explosive product much as silver does but the reaction occurs more quickly in the case of gold so
I avoid the use of ammonia if I am expecting to recover gold.
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cyanureeves
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if you add ammonium hydroxide to auric chloride you might drop gold fulminate.i dissolved some plating foils and stripped a gold plated chain with
hydrochloric acid and peroxide.i dissolved the gold in aqua regia and dropped it with sodium metabisulfate but when i added ammonium hydroxide to the
drop i got a blue solution.i decanted the blue solution which was obviously copper ammonia complex.i didnt even dry the dropped gold but instead
redissolved in agua regia and when i added ammonium hydroxide to the auric chloride i got an orange precipitate.
[Edited on 8-12-2013 by cyanureeves]
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blogfast25
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@cuanureeves:
Congratulations! You've reported the first ex nihilo creation of carbon on SM! Cooler than lead to gold, I'd say... 
Jokes aside: 'fulminating silver' and 'silver fulminate' aren't the same thing at all:
http://www.sciencemadness.org/talk/viewthread.php?tid=2179
Whether 'fulminating gold' actually exists is doubtful but I'm no expert...
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Tdep
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For fulminating gold check out this site someone linked to me when I was on a similar topic. Very interesting.
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bfesser
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Please, not that <em>Lateral Science</em> site again! Just so you're aware, that site is heavily <em>fictional</em>. The
proprietor came around here a few weeks ago advertising for his new novel (you may find the post in <strong>Detritus</strong>. I caution you to be skeptical of anything you read on that website! It can be
tricky to sort out the factual information from the rest of it.
[Edited on 14.8.13 by bfesser]
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Boffis
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That fulminating gold exists is not in question; only is constitution and nature are in doubt.
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phlogiston
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Quote: Originally posted by Boffis  | Aqua regia tends to leave a lot of silver in the residue because AgCl is highly insoluble.
- snip -
Any silver in the original insoluble residue can be leached with ammonia solution and then precipitated onto copper wire in the same way.
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If you leach with thiosulphate instead, you can avoid the ammonia. The silver precipitates nicely with copper from the thiosulphate solution as well.
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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cyanureeves
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so the orange stuff that drops when adding ammonium hydroxide to auric chloride is called an alkoxides?amino complex of gold?gold? i have been trying
to use this to electroplate with and it just aint so great even though it is used by some platers in gold cyanide solutiions.sometimes i know i have
gold in a gold chloride solution but not enough to actually drop and melt down but i can almost always easily get some"fulminate of gold" i have read that concentrated ammonium hydroxide is used but i get a brighter dust
if i use store bought ammonium hydroxide. i even read that its done by bubbling ammonia through the solution.so the story about Johann Rudolph Glauber
(1604 -1668), a German alchemist etc... is not true? he looks so chemicky and "i'll blow you up with my gold" and all,in that black and white
thumbnail.
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bfesser
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Thread Split
14-8-2013 at 14:55 |
bfesser
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Threads Merged
14-8-2013 at 14:57 |
blogfast25
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| Quote: Originally posted by cyanureeves | | so the orange stuff that drops when adding ammonium hydroxide to auric chloride is called an alkoxides?amino complex of gold?gold?
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It's certainly NOT an alkoxide. Alkoxides are the salts made up of an alkoxide anion and a metal cation.
Typically when reacting short chains alcohols with alkali metals they form, e.g.:
CH3OH(l) + Na(s) === > NaOCH3(solvated) ['sodium methoxide'] + 1/2 H2(g)
Or CH3CH2OH (ethanol) with K gives KOCH2CH3, 'potassium ethoxide'.
These are strong bases and they hydrolyse strongly in the presence of water, yielding the alcohol and a hydroxide.
[Edited on 15-8-2013 by blogfast25]
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AJKOER
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| Quote: Originally posted by cyanureeves | if you add ammonium hydroxide to auric chloride you might drop gold fulminate.i dissolved some plating foils and stripped a gold plated chain with
hydrochloric acid and peroxide.i dissolved the gold in aqua regia and dropped it with sodium metabisulfate but when i added ammonium hydroxide to the
drop i got a blue solution.i decanted the blue solution which was obviously copper ammonia complex.i didnt even dry the dropped gold but instead
redissolved in agua regia and when i added ammonium hydroxide to the auric chloride i got an orange precipitate.
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Yes, this source ( see http://gold.atomistry.com/gold_and_nitrogen.html ) confirms that adding ammonia to aqueous auric chloride does form a fulminate of gold. To quote:
"The so-called " fulminating gold" has long been known, and derives its name from its explosive character. Its composition varies with the mode of
preparation. Explosive products classed as fulminating gold are obtained by the interaction of ammonia or ammonium salts and auric oxide; by that of
ammonia or ammonium carbonate and auric-chloride solution; and by that of ammonia and the sulphuric-acid and nitric-acid derivatives of gold. The
colour of the product varies between green and brownish yellow; and on heating, percussion, or rubbing it decomposes explosively into gold, nitrogen,
and ammonia. The explosive power is augmented by boiling with water or potassium-hydroxide solution, and by careful heating at 100° C. It is reduced
by mixing the powder with salts of the alkali-metals or alkaline-earth metals, and with metallic oxides. Raschig assigns to the product obtained from
auric oxide the constitutional formula NH=Au-NH2, the union of both nitrogen atoms with gold being indicated by the small proportion of nitrogen
eliminated by boiling with water, alkalies, or acids. He has shown the product obtained from auric chloride to consist of this substance with an
admixture of a chloro-derivative, NH=Au-Cl."
So the substance formed is reputedly a mixture of gold hydrazide NH=Au-NH2 and NH=Au-Cl. However, this more recent source (see http://publik.tuwien.ac.at/files/PubDat_170506.pdf ) suggests that the actual "constitution cannot be expressed by a simple formula."
The Atomistry.com source also goes on to state:
"Another method of preparation has been described by Jacobsen.
Silver nitrate reacts with aurichloric acid in accordance with the equation
4 AgNO3 + HAuCl4 + 3 H2O = Au(OH)3,4AgCl + 4HNO3.
The brown precipitate formed is converted by ammonia into fulminating gold, which after drying explodes violently downwards when touched with a knife.
Jacobsen regards it as having the constitution Au(OH)2NH2 or (AuN,2H2O),H2O. When boiled with potassium-hydroxide solution, it is converted into a
blackish-brown substance of even more explosive character, probably having the constitution Au(OH)2NHAU(OH)2."
[Edited on 15-8-2013 by AJKOER]
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blogfast25
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Sigh. As pointed out above, it's not 'fulminate of gold', but 'fulminating gold'.
'Fulminates' are salts of the CNO- anion. 'Fulminating gold' doesn't contain any carbon.
[Edited on 16-8-2013 by blogfast25]
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AJKOER
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Thanks Blogfast as it was not my intention to imply that 'a fulminate of gold' is 'gold fulminate'.
The point instead was that apparently the preparation of 'fulminating gold' can yield one of a family of 'fulminating gold', with varying colors
noless, depending on the mode of preparation  . Perhaps more correctly (but
more awkward or less clear?), 'a fulminating gold'.
This is one reason why, if possible, one should use the actual formula (which appears to be somewhat indefinite, hence not precisely correct, in the
current content) so as to reduce confusion.
Where is an English major (or even a minor) when you need one.
[Edited on 16-8-2013 by AJKOER]
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Fleaker
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I can say this much: do not make any gold solution ammoniacal. The bright yellow to ochre powder that results is indeed quite dangerous. DO NOT DO IT.
It snaps, crackles, and pops leaving a fine purple-gold coating over everything.
You can obtain highly pure gold from it in some instances but there are FAR better ways.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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AndersHoveland
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| Quote: | | Fulminating Gold may be prepared by reaction of auric chloride, AuCl3, with aqueous ammonia, NH4OH. The explosive precipitate is mostly (ClAuNH2)2NH,
but on washing with excess ammonia, there is hydrolysis to more explosive form, with an olive-green color, in which gold atoms are complexed to amine
groups in a square planar configuration, and in which some of the amine groups cross-link between two gold atoms. The exact structure is not known,
and the crystals appear to be amorphous. The more explosive form does not appear to contain chlorine. Fulminating gold explodes with a violet cloud of
gold particles. Fulminating gold a dangerously sensitive explosive, and tends to be much more sensitive to friction than to impact. It is thermally
stable up to 200 °C, and decomposes at 210 °C often with explosion. |
I'm not saying let's go kill all the stupid people...I'm just saying lets remove all the warning labels and let the problem sort itself out.
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AndrewCampbell
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Thanks guys for the comprehensive instructions. It would definitely help in the separation process which could get tough at times especially
extracting silver from a mixture of copper. I guess it should take a few trial and error sequences before deriving with the perfect solution.
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