guy
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Transition metal peroxyacetates?
I tried to make a copper acetate by leaving a few pennies in vinegar. About 2 weeks passed and nothing seemed to happen. Then I decided to add 3%
Hydrogen peroxide to it. In a few minutes the solution turned blue. When I added NaOH, a green blob (kind of like Ferrous hydroxide) with moderate
bubbling. Then after it settled it turned to a regular copper hydroxide.
The same thing happened with Nickle.
Why was there bubbling? Was it a metal peroxyacetate or did the H2O2 just sped up the reaction?
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BromicAcid
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Did the bubbling come from the gelatenous blob or did it seem to rise from nowhere in the solution?
Was the soultion warm?
What do you mean | Quote: | | Then after it settled it turned to a regular copper hydroxide. |
Could be a metal peroxyetanoate but if it was it decomposed readily. Or it could have been basified H2O2 reacting with organic material to oxidize
it. Or metal ions catalyzing H2O2 decomposition. Or if the origional metal object that you were trying to dissolve was still in the solution the
acid could have caused extensive pitting would could have acted as a high enough surface area substrate to catalyze H2O2 decomposition. Could have
been a number of things.
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guy
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| Quote: |
Then after it settled it turned to a regular copper hydroxide
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I meant that before it settled it was like a dark green or blue blob with bubbles coming from the blob. And after a while it looked like normal
copper hydroxide (blue precipitate).
I don't think the solution didn't got warmer
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Marvin
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Copper dissolves in acid faster when you add an oxidising agent, its not really strong enough to liberate hydrogen.
Hydrogen peroxide is unstable in basic solution decomposing to the expected water and oxygen. Its most stable in very mild acid. As for the odd
green colour there is a basic copper acetate called verdigris that I think is blue/green, rather than the very light blue of fully hydrolysed copper
hydroxide.
[Edited on 9-7-2004 by Marvin]
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guy
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I should have noticed it earlier.
Apparently, the copper pennies must have been contaminated with nickel, which explains the green blob.
I tried later again and there was very few bubbling. Only bubbles came from the nickel.
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The_Davster
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What country's pennies were you dissolving? A while ago I had been dissolving the insides out of copper canadian pennies with HCl and the acid
turned green. When the now hollow pennies were ripped open, there was clearly lots of green substance showing.
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guy
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They were US pennies. After dissolving them, the solution turned blue.
The nickel (from US nicKel coins) solution was bluish turquoise. When precipitating them they were green BUT aren't nicel solutions supposed to
be green?
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I read somewhere on the internet that peroxyacetic acid can dissolve aluminum but whenI tried it it didnt seem to work
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Polverone
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Copper can form a variety of green/blue/purple compounds, so don't assume that you have nickel just because you see green. US nickels are made of
a 25% Ni, 75% Cu alloy.
Speaking of pennies and vinegar, I remember that when I was young I mixed salt and vinegar to clean pennies by a method that I'd read in some
book. After a couple of minutes in the solution, they had beautifully clean surfaces. But they rapidly tarnished when washed off and exposed to air.
Even more interesting, I recall that after being used for some time, the mixture grew more potent. Dropping a penny in the solution would remove
tarnish instantly. I don't know if this was from some sort of catalytic effect from the metals being dissolved, from evaporative concentration of
the liquid, or something else. The blue-green liquid did leave some lovely colored big salt crystals when it finished evaporating.
PGP Key and corresponding e-mail address
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guy
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nevermind this post
[Edited on 10-7-2004 by guy]
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