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Author: Subject: Acid mixtures that dissolve gold
zed
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[*] posted on 26-2-2021 at 18:08


Well, HCl/H2O2 will sure dissolve Platinum, but the reaction doesn't seem to be very robust.

The H2O2 liberates Chlorine, but the H2O2 needs constant replacement, as Platinum decomposes it.

Folks sometimes use the process to dissolve finely divided spent catalysts, or to leech the Platinum out of Platinized Carbon.

For dissolving Chunks of Platinum, perhaps messy Aqua Regia is the was to go. It's something I have to do soon, and I lack enthusiasm. Clouds of toxic red gas.... Yuk! Still, it does produce the product I need, straightaway, and in its pure form. Chloroplatinic acid.

Thought Electrolysis with HCl might also work. Or, reaction with elemental Chlorine.... But, each has its drawbacks, and Aqua Regia is tried and true. Additionally, Nurdrage has provided a decent Youtube video.

Oh yeah, Gold? Gold is easier. Some of the More Arcane Precious Metals, aren't touched by any reagent we have discussed. You can fuse them with Molten Alkali Salts though.

Well, I can't provide a link. This odd Southern guy, does interesting work, but perhaps he has rubbed Youtube, the wrong way. One day, you are a star.... The next day, you are gone.

[Edited on 27-2-2021 by zed]
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Panache
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[*] posted on 28-2-2021 at 04:47


I find aqua regia dissolution of precious metals are best performed using a behive type setup. Basically your metal and aqua regia are in a beaker. This has a larger inverted beaker on top. Both sitting in a tray with water...

[Edited on 28-2-2021 by Panache]
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ChemTalk
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[*] posted on 28-2-2021 at 07:45


>> This odd Southern guy, does interesting work, but perhaps he has rubbed Youtube, the wrong way. One day, you are a star.... The next day, you are gone

Who was that?
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Panache
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[*] posted on 2-3-2021 at 04:33


Quote: Originally posted by Panache  
Quote: Originally posted by Lion850  
Concentrated HCl with I2 dissolved in it dissolves gallium (fast!) and also tin (slower, but faster than HCl on its own). If I had a bit of gold to spare I would try, but I don't have.


So i just tried straight i2 ar rt with gold...no reaction. Sealed the tube and heated no reaction. I reacon addinghcl will do sweet fa.
Illletyou know


Ahh yeah i was completely wrong...no metallic gold.
So iodine and hcl most definitely dissolves gold.
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zed
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[*] posted on 2-3-2021 at 09:24


So, Panache. You are suggesting to place this project in a shallow pan of water... and to heat the whole thing? One large beaker, inverted over a smaller beaker containing Aqua Regia and Metal?

Thereby, trapping the noxious fumes, in the water bath?

I like the simplicity.
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[*] posted on 2-3-2021 at 11:02


Quoting Panache:
Ahh yeah i was completely wrong...no metallic gold.
So iodine and hcl most definitely dissolves gold.
Unquote

Hi Panache very interesting, can you please give more details? Did the gold go into solution with no ppt? Gold monoiodide is yellow-greenish according to Wikipedia; did you see these colors? Do you know the weights of reagents involved?
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[*] posted on 2-3-2021 at 12:17


Alright, that Precious Metals poster, is still on Youtube. Not excluded.... yet. And, maybe he isn't a Southern Guy.

Not Gold, but a very interesting procedure. Fusion of Platinum Group metals, in molten Alkali. Precipitation via Barium Salt.

https://www.youtube.com/watch?v=gV2N2Jqpo6w

[Edited on 2-3-2021 by zed]
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Panache
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[*] posted on 2-3-2021 at 16:33


Firstly zed, yes it's fantastic, you can even use your kitchen sink as the pan of water and run a constant water stream down the drain. I once did a larger one in a 20L pp bucket, over the bucket i had a shallow wider bucket and then over this a towel and the entire thing ran under the shower, once they get bigger they really don't need any heating.
And lion 850, ahh you're australian.
So i grabbed i guess enough gold plated pins to cover the bottom of a 50ml beaker, i then added i guess about quarter this volume in iodine. The pins were very fine. i then sealed the top with some silicon film and warmed the underside melting the iodine. not much happen. I let it cool and added some hcl conc. It began working upon the copper (the pins were gold plated over copper) but i saw no attack of any gold surfac. After about 30minutes i got bored left it for three days snd then when i looked again there was no gold left on any of the pins but srangely there were pins left, well partly.
I rinsed them well to ensure that the observation was correct.
And yes absolutely a ppt had formed and it was yellowish green. i haven't filterred it yet, prtobably wont. as it would also contain copper nickel al compounds also.
With this Au(!) iodide, does it dissolve other metals liberating gold netal?
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[*] posted on 2-3-2021 at 16:42


if you know how, with only HCL, Gold CAN BE dissolved. PERIOD ;-)
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[*] posted on 6-3-2021 at 16:32


Quote: Originally posted by pneumatician  
if you know how, with only HCL, Gold CAN BE dissolved. PERIOD ;-)


ok, ill bite, what do you know? I find it difficult to believe you need only hcl, i mean one would need at least a beaker and water (because HCL is a gas at stp.....)
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[*] posted on 9-3-2021 at 07:41


Quote: Originally posted by Panache  
Quote: Originally posted by pneumatician  
if you know how, with only HCL, Gold CAN BE dissolved. PERIOD ;-)


ok, ill bite, what do you know? I find it difficult to believe you need only hcl, i mean one would need at least a beaker and water (because HCL is a gas at stp.....)


oh yes, period, I asume you are right... of course you need a table, a pair of hands, a bottle to contain the hcl, a company producing hcl if you not make your own and etc etc etc ad infinitum, ok? right? but the point here is Gold dissolved with only hcl, in water or gas, in a beaker and etc etc etc, ok? right? :-D

ok, after all this ironic mumbo-jumbo... what is Gold?

ok, right, a metal, produced in the big bang, star dust and more and more mumbo-jumbo...

Stop! Gold is a COMPACT BODY, right?

so, et dividant dissolvere, I need to say ironic free something more??

in some thread here a guy "dissolved" Gold with chlorine only.

Sapere aude!
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[*] posted on 9-3-2021 at 07:55


possibility #979831: gold in hydrochloric acid, ozone generator bubbles (slowest possible method)



[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 9-3-2021 at 09:27


With ONLY HCL, no more, no less!

https://www.youtube.com/watch?v=oevJf2aYHjo
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[*] posted on 9-3-2021 at 11:12


^my post wasn't responding to you so much as providing a humorous way to dissolve gold, but, what I would suppose is, you can dissolve Au in "pure" hydrochloric acid (HCl@H2O) using a membrane-cell setup (no membrane likely = gold all over cathode), but this isn't actually simple to set up in practice



[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 13-3-2021 at 22:45


(4) works quite well. Here, 35% H2O2 is (relatively) inexpensive and is used in gallons for swimming pool treatment. Swimming pool chlorinator tablets Trichloro-S-Triazinetrione are a good chlorine source.The reaction seems to work at near neutral pH.

I tried various methods without HNO3 in order to simplify subsequent reduction. Also 35%H2O2 was -much- easier to obtain OTC locally with no hazmat shipping.

Want to be Auric Goldfinger? (Ian Fleming reference) Spill a beaker of aqua regia + gold on your hands. Instant Purple of Cassius! I got to the sink before the acid did any significant damage, but the gold precipitated in my skin -instantly-. Lasted for weeks.

Another reaction with H2O2 and gold plated copper: H2O2 and CH3COOH happily dissolve copper and leave gold behind. 3% H2O2 and 5% acetic acid work albeit slowly leaving pretty blue-green cupric acetate and little gold flakes.
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