chemdude118
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Mysterious Reaction
I was performing an experiment that my friend told me about. Basically you put a small amount of copper carbonate in hydrogen peroxide, 3%. it will
change colors from blue to dark brown. I filtered this mixture and the filtrate was green while the filtrand is brown. I repeated the experiment but
this time the filtrate was brown and again the filtrand was brown. Does anyone know what has happened here? All that I know is that it is a copper
compound because it made a solution of potassium ferrocyanide turn coppery-pink color. It was also giving off a gas that smelt like ozone.
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AndersHoveland
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The reaction of hydrogen peroxide with aqueous titanium(IV) gives a brightly colored peroxy complex that is a useful test for titanium as well as
hydrogen peroxide.
http://en.wikipedia.org/wiki/Transition_metal_dioxygen_compl...
http://www.ncbi.nlm.nih.gov/pubmed/12465953
Elemental titanium shows good corrosion resistance against alkaline hypochlorite. Interestingly, however, alkaline solutions of hydrogen peroxide are
known to corrode titanium! It is thought that the HOO- anion forms a complex with the protective surface oxide layer, Ti(OH)2O2 (with titanium still
in the +4 oxidation state), the soluble complex later hydrolyzing into Ti(OH)4 and H2O2.
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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chemdude118
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I'm sorry, I don't understand what exactly your telling me. I don't have any titanium compounds
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Endimion17
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AndersHoveland, and what does titanium(IV) have to do with his copper reaction?
In fact, peroxide indicator is titanyl (TiO<sup>2+</sup> sulphate,
because it becomes brownish red, yielding peroxotitanyl (TiO<sub>2</sub><sup>2+</sup> which has nothing to do with ligands. It's an oxycation.
chemdude118, where did you get "copper carbonate"? Could it possibly be basic carbonate, and you prepared it yourself?
I'm looking at the reaction at the moment. It doesn't turn brown at once. It goes from turqoise (basic carbonate) to more green than blue suspension,
and then slow effervescence of oxygen begins. Color slowly turns to olive green, oxygen increases slightly.
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chemdude118
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I made my own copper carbonate from sodium carbonate and copper sulfate. It did undergo the changes that you described. Can you describe what happened
to me?
Thanks
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Endimion17
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I'm looking at the test tube and apparently, there are two solids inside. An olive green and an actual green one. That's interesting. Maybe the first
one is very unstable, perhaps even a bit photosensitive? Or maybe it's just one solid which color differs because of the particle size?
I really can't tell what was that olive green solid at the begining. Maybe some kind of cuprate of copper?
Homemade basic copper carbonate is really not the stuff you want to begin with as it's too complex. Who knows what happened. The mixture looks really
weird. I bet someone did it several decades ago and now it's in an old book somewhere.
But I can tell you this. Dried and heated, it gives copper(II) oxide. It really could be some kind of cuprate.
[Edited on 31-8-2011 by Endimion17]
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woelen
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It is an unstable peroxide of copper. A very simple and instructive experiment is to add a solution of copper sulfate to a solution of NaOH. This
gives a blue precipitate of Cu(OH)2. If you add some H2O2 to this, then it turns dark brown or even black. Olive green colors also are possible.
The copper carbonate, made from aqueous solution is so-called basic copper carbonate (copper hydroxide+carbonate). This shows a similar reaction. Your
olive green, brown and possible black products are a complicated mixture containing copper peroxide, carbonate and hydroxide.
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chemdude118
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When I filtered my solution, it was brown but had a turquoise colored substance in the center.
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Endimion17
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It could be piece that never got the chance to react.
Anyways, as Woelen told you, it's a complicated mixture. Try exposing it to the ultraviolet rays for a couple of minutes.
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chemdude118
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Right now its cloudy and dont have batteries for my UV light.
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chemdude118
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I mixed it with a lot of vinegar and the color changed to a bluish-green.
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chemdude118
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When you mix the copper carbonate and hydrogen peroxide, let it stand for 20 minutes. Then filter the mixture and you should get a green solution. It
is an indicator. It is yellow in acids and green in neutral or base.
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#maverick#
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Quote: Originally posted by chemdude118  | | When you mix the copper carbonate and hydrogen peroxide, let it stand for 20 minutes. Then filter the mixture and you should get a green solution. It
is an indicator. It is yellow in acids and green in neutral or base. |
that sounds interesting i will try this next time i am in lab
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