MeshPL
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Copper, ammonia, vinegar, acetone and I don't know what happend.
Hello everybody!
I was electrolysing 25% ammonia using copper electrodes. I ran electrolysis until most of the copper started to deposit on cathode. I was left with
blue tetraaminacopper hydroxide in aqueous ammonia.
I put a piece of copper wire to see if it will be etched or something, but nothing happend.
Just for fun I poured few times more 10% vinegar, but nothing happend. Vinegar is not very strong.
As far as I remember I also added some acetone but also nothing happed.
However after a few days the liquid turned dark brown, simmilar to unacidified Fe(III) but more reddish, the piece of copper wire seems etched, and
there are small probably copper particles particles floating in liquid. The liquid still smells of ammonia and acetone but not vinegar. When I opened
the jar I found out it built a little pressure.
Does anyone know what is responsible for the color change?
[Edited on 22-8-2015 by MeshPL]
[Edited on 22-8-2015 by MeshPL]
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CharlieA
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How do you know what was left in solution after the electrolysis?
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aga
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Please put random experiments with no reference to documented research in Beginnings.
[Edited on 22-8-2015 by aga]
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Bert
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Thread Moved
22-8-2015 at 08:31 |
MeshPL
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How do I know what was left in solugion after electrolysis?
1. From the colour. (Nice blue, not turquise, like in copper ammonia complexes)
2. From what could have potentially happen and was likely to happen. E.g. there could be a slight chance it produced hydrazine/hydroxylamie, but since
I haven't heard of it producing them (compounds with not a lot ways to synthetise them), this theory can be neglected.
I wouldn't be surprised if it would produce some nitrites though.
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aga
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I've never seen a Turquoise copper/ammonia complex.
Only seen TetraAmmineCopper(II)Sulphate though.
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MeshPL
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No, it wasn't turquise!
Plain hydrated copper is turquise, anx my solution wasn't and is not now.
It was blue like you would expect from tetraamina copper sulphate/hydroxide/whatever.
Like this:https://en.m.wikipedia.org/wiki/Schweizer%27s_reagent
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WGTR
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I use tetraamminecopper(II) sulfate on occasion to etch copper foil using a tin resist. The ammonia concentration has to be very high to etch copper,
and even then it is a slow process. Etching thin (1-2mils for example) copper foil may take a half hour or so, with stirring.
Since the ammonia has to remain concentrated for etching purposes, it is necessary to perform the etching in a sealed bottle.
I use 30% ammonia to make up the solutions. I doubt the store-bought concentrations would work for etching copper.
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PHILOU Zrealone
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For etching you also need oxygen from air...usually drip the Cu Inside the concentrated NH3 and allow to "dry" in the air.
If the copper remain under the NH3 surface, it remains shiny...the solution turns slowly blue because the CuO layer is dissolved and has to reform
upon contact with air...an hermetically closed bottle will depress while O2 is consumed.
It must be opened from time to time to allow fresh air to enter the bottle.
The darkening is only the result of the polymerization of aceton upon contact with ammonia...you get acetone imine polymerization mixed with
condensations and crotonisations... see mesityl oxyde and phorone...
The mix can become resinous orange-brown-black in color with a sweet weird smell (after amonia has evaporated).
Hydrazine will never form if Cu(+) or Cu(2+) is present.
[Edited on 22-8-2015 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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MeshPL
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Acetone and ammonia condensation?
Never heard of it, but that explains everything. I know what I will buy when I'll visit hardware store next time.
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Metacelsus
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Acetone and ammonia condensation is, in fact, the first step in making TEMPO. It's not a very clean reaction, producing a lot of gunk besides
triacetonamine.
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