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UnintentionalChaos
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Question on copper compounds
I apologize if this is a stupid question and I am wasting your time, but it has been bothering me for a while now. Over a year ago I put copper wire
coils in vinegar (white, 5% acetic acid). The idea was to make copper acetate and use the solution to fix some natural dye colors to wool (it makes a
very nice mint green by itself) because almost anything with copper ions seems to work. It was fairly slow to form solution and in my impatience, I
added NaCl and some crystalline citric acid in hopes of making the copper dissolve faster. It worked, but afterwards the bottle was left (cap on, but
not necessarily perfectly airtight) for a very long time in a corner. All the reactants were still in the bottle, as I kept repleneshing the mix after
each use. When I came home from college for thanksgiving break (many months of being undisturbed), I noticed that the solution had become clear (as
opposed to blue) and a layer of slightly green tinged blue precipitate had affixed itself to every surface the solution had been in contact with.
Considering the ingredients, I could expect some random proportions of copper chloride, copper acetate, and copper citrate. The amount of copper that
was consumed did not lead me to believe that any of these three chemicals could have reached a saturation point, but i could be wrong. I scraped out
the precipitate, crushed it and washed it several times with water to remove any NaCl. None of the precipitate dissolved during washing, at least
nothing that would form the typical blue copper salt solution. When dried and powdered, the precipitate was an extremely fine light blue powder with
only a tinge of green. In an attempt to salvage the mixture (since i had no idea what to do with it) I mixed it with an excess of NaOH and got a
precipitate of blue green granules which seemed to consistently have a very dark, nearly black, center, despite my best attempts at powdering the
original chemical/chemicals. Again, I decanted the liquid and washed the precipitate multiple times with water and for some unknowable reason, 70%
isopropanol (maybe I was looking for a subconscious excuse to explain the missing alcohol which i was busy making burn violently by squirting onto the
extremely hot back wall of the fireplace). I assumed what I had was copper hydroxide, but all the descriptions I hear of it are of a very light blue
substance and I had something that was extremely dark green tinged with blue that appeared dark gray in some lights, so I doubt that was what I had. I
finally gave up trying to figure out what it exactly was tonight and roasted it over a wood fire in a crude stainless steel crucible for 10 minutes
until it turned entirely, intensely black. This, I can probably safetly assume, is CuO, which should have resulted from roasting copper hydroxide
anyway. Can anyone give me any clues as to what compounds I may have had at any stage in this...lets just call it a mess?
And this is an idiotic question, but can i produce more CuO from the following series of reactions? I have access to HCl and NaOH, but not to the
copper sulfate or nitrate that I have seen discussed for production of CuO in other threads.
Cu+2HCl->CuCl2+H2
CuCl2+2NaOH->Cu(OH)2+2NaCl
Cu(OH)2->CuO+H2O
I'm pretty sure I got this right, but I haven't had a chemistry class in 4 years and I dont have any textbooks lying around to check if the second
step will work.
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YT2095
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the reaction will work, although the 1`st stage will be dreadfully slow, you`ll need to add a pinch of Chlorate to it to start it off, H2O2 should
work also I beleive, then just make sure this soln with copper metal gets plenty of air exposure.
for stage 2 I tend to use a Carbonate, sodium or potassium will do.
simple heating of this copper carbonate will give you your CuO, it`s easy to tell as the powder goes from green/blue to pure black.
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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UnintentionalChaos
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Thanks
I found the thread on copper etching with HCl just after I posted this. My supplies are not particularly diverse but I can get the peroxide in some
crappy, low % solution. Should still work for getting it started though. Is there any potential hazard to using the hydroxide instead of carbonate? I
trust the purity of the hydroxide, but not so much the carbonate. I have a significant quantity of the hydroxide for soap making so I'm not
particularly worried about using it.
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12AX7
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Use sulfate or nitrate instead of chloride. Strong solutions of chlorides form a green tetrachlorocuprate ion, which produces chalky green copper
oxychloride when neutralized, rather than the blue fluff you want.
True copper hydroxide decomposes at boiling water temperatures. Green oxychloride does not. On roasting, it disproportionates to CuO and CuCl2, the
latter which vaporizes easily, giving off irritating smoke. You can boil the oxychloride in a base to disproportionate it, at least on the surface,
giving black CuO, at the expense of more base.
Tim
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UnintentionalChaos
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What if I used an excess of copper in the first reaction? Shouldn't that leave a fairly pure CuCl2 endproduct? (I'm getting this idea from woelen)
"Initially, an oxidizer is needed to dissolve any copper metal in the hydrochloric acid. Hydrochloric acid itself is not capable of dissolving copper
metal (see table of electrode potentials). With the help of some oxidizer, however, copper metal can be dissolved. This results in formation of the
tetrachloro cuprate (II) complex. E.g. with H2O2:
H2O2 ---> H2O + O.
O. + 2H(+) + Cu + 4Cl(-) ---> H2O + CuCl4(2-)
The CuCl4(2-) ion is essential to further working of the copper etching liquid. This complex ion is capable of oxidizing copper metal:
CuCl4(2-) + Cu ---> 2CuCl2(-)
The copper (I) complex CuCl2(-) in turn is very easily oxidized by oxygen from the air, provided sufficient acid and chloride is present:
O. + 2CuCl2(-) + 2H(+) + 4Cl(-) ---> H2O + 2CuCl4(2-)
So, once you have some copper (II) in solution, the etching liquid works great, using oxygen from the air as oxidizer. This oxygen is absorbed from
the air extremely easily. So, you first use a small quantity of soluble oxidizer (e.g. H2O2, KClO3) to get the reaction started and once you have
sufficient CuCl4(2-) in solution, you simply use oxygen from the air as oxidizer.
When the liquid becomes very dark at a certain moment, then add a litte concentrated HCl and let it stand in contact with air for a while and then it
is ready to be used for a new batch. Works really great and is very cheap. The waste product is quite interesting as well, it makes fairly pure CuCl2
on evaporation."
The reason the reaction will drop off...do the tetrachlorocuprate ions dissosciate back into chloride ions as the chloride ion concentration starts
running out or do they remain intact, and the remaining free chloride ions simply run out?
In either case, if woelen is correct, then "fairly pure CuCl2" is all I'm looking for. In fact, I was planning on splitting the batch, saving half for
coloring pyrotechnics (sold as campfire blue on skylighter for making pinecones and woodchips that color fires blue and green) and the other half for
converting to CuO for thermite. Well, ok, maybe most of it for thermite. Since I am roasting it in a makeshift fume hood (the fireplace) I'm not too
worried about CuCl2 vapor from copper oxychloride contamination, but I'd rather not have a large portion of my yields going up the chimney. I wish I
had access to nitric or sulfuric acid. It sounds like that would make my job a lot easier. Thanks for all your help.
Actually, one more thought. Does sodium hypochlorite do as good a job oxidizing copper as it does oxidizing iron? And if so, could I then just bypass
the H2O2 oxidation step and dissolve the oxide (I (hell, i wouldn't need all these steps if it did),II, mix?) in HCl, then proceed?
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Aqua_Fortis_100%
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I wish make differents Thermites for compare them... And this CuO thermite (and other nobles metals thermites) looks very interesting for me..
I very interested in this CuO and planning make it... Because now i have some grams of superfine mesh and good Al powder  ..
One time i read (in E&W forum) which the thermite made from this CuO is extremely explosive and if confined in a pipe can be detonated and will
throw metallic Cu and shrapnell of pipe ,making very loud explosion...
think which work if one making and reacting a conc. copper sulfate solution(almost pure ,professional fertilizer grade) with caustic soda and then
decanting the Cu(OH)2 precipitated and washing and decanting several times to remove the sodium sulfate formed, and after, pour the water excess out
and heating Cu(OH)2 to form CuO..
CuSO4 + 2 NaOH ----> Na2SO4 + Cu(OH)2
and
Cu(OH)2 --heat---> CuO + H2O^
.....
well , I tried the first part of the experiment:
i get 150g of nice cristaline CuSO4*5H2O which has been dissolved in 1500ml of water .. some not dissolved impurities remaining in the solution,
then i filtrate through the coffee filter.. then measure 75g of 65% NaOH and add more 25g to make an excess of NaOH, and dissolving this in 700ml
of water... then i filtrate with another coffee filter and let cool...
after, add the NaOH solution in the CuSO4*5H2O solution...immediately a blue mass precipite...
(I still washing the precipitate.. maybe tomorrow i will separe and heat the Cu(OH)2 and post here the results..)
[sorry about my very poor english, because this is not my language)
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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12AX7
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Boil the solution right now. CuO is a whole hell of a lot easier to filter than Cu(OH)2.
Tim
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Aqua_Fortis_100%
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Thanks 12AX7!!
Right i now washing the precipitate and decanting to remove the Na2SO4 and SPECIALLY NaOH which can eat my metal pan..
but in a little while ,i will boil the the solution and heat even more the black-green(before it is blue mass with lots of white mass..after, is this
black-green mass.. why??? )
------
but still have doubt: this thermite with CuO can be light with a fuse?
( my Fe2O3 thermite is light with a simple matche or fuse (because the highly fine Al, i think...) and burn extremely fast with very bright light,but
don't is capable of melt or to cross a fine steel plate..I tried add small amounts of coarser Al powder (from blender + Al foil method),but still dont
work... what i can do?
thanks again!
[Editado em 25-12-2006 por Aqua_Fortis_100%]
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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12AX7
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If the aluminum is fine enough to light with a match or fuse, then it'll light the same in any thermite.
Tim
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Aqua_Fortis_100%
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but, if my Al powder is too reactive why the reason which I haven't sucess with PbO/Al thermite??? even this with Fe2O3 not iniciate and no lead
metal was visible... i think be maybe because the very low boil point of lead,but i'm not sure..(first i mix some Fe2O3 to PbO aiming make it less
hard to light.. put the PbO-Fe2O3/Al in a steel can and put on this some Fe2O3/Al to initiate... put on this the fuse and light ... in the can i see
a yellow powder substance on the walls of the can..) .
maybe Pb3O4 work better...
what your think ?
(sorry again for my poor english and also to distort the thread...)
[Editado em 25-12-2006 por Aqua_Fortis_100%]
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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12AX7
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In my experience, PbO burns much like CuO, but perhaps less well. Both, in loose piles, tend to burn (in a flash) only the outside layer, leaving
much of the pile intact.
I have a video of semi-confined PbO burning smoothy, so it certainly works.
I usually use magnalium +100 mesh, as it's the easiest for me to make.
Tim
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Aqua_Fortis_100%
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if you say which works, then i agree... and think about this if ones build a good method for make fine Al powder (any grinder machine which makes
coarser Al powder and then pour this in a ball mill with steel balls.. think on a cheap and/or natural energy source for mill,such as small natural
waterfalls ( putting a small or big "turbine" sustained with a long pipe - to water not spill in mill - in the waterfall to provide the cinetic energy
for the mill which can be open from time to time to refresh the air and oxygen for the Al) or ther interesting thing ..),can recycle the PbO made from
"conventional" nitrite synthesis and reuse them for make more nitrite (very useful for some "homemade" explosives such CTMTNA, DDNP, etc..), because
the lead here is very expensive chemical(from fishing weights ),and the "cheap" lead from old batteries has A LOT of impurities.. the problem, again
should be the low Boiling Point of lead produced which will should instantly vaporize..
or then use in a controlled ratios and additions the Al powder obtained and a molten nitrate on a burner or other heat plate..but this method should
be MUCH more dangerous to make and i heard which the yield of the xNO2 is very crappy..
2 Al + 3 xNO3(l) ----> 3 xNO2 + Al2O3 + more heat
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ok, about the CuO, i made 3 hours ago a small batche  .. put some (i not know
the exact measures -weight - because i have no an accurate scale at the moment..) of the washed and decanted Cu(OH)2 in a enameled steel pan and heat
slowly in stove.. lots of water vapour giving off.. and the green-black substance was after in aprox half hour reduced almost totally the volume and
converted in a totally amorphous black cake and this in a powder ... dry this...make more fine powder ...small amount has collected..(some of CuO
still to stay in a wall of the pan in form of very thin layer..then i scraped the layers with a spoon to get more CuO)
some minutes after this i tried make the CuO/Al thermite:
first i measure with a teaspoon the follow proportion: aprox.. 2 pbv of CuO to 1 pbv of Al powder..
(can you tell me the exact proportions? by weight is right ,but such i haven't accurate scales, pbv is needed..thanks).
using gloves, put these on a paper ,and with the roller and knife , mix all together, as homogeneous as possible...
then put small amount of the resulting gray powder, on a small nickel coin..(and coin on ceramic) ..
put a match head on top of pile and light with an another match.. the result was VERY impressive!!! very fast burn ,very light
evolved and also a instant white cloud..like flash powder!!! My eyes stays blind for some moments! ...unfortunately not all the pile burned...since
probably are wrongs in "eye" measurements...
i'm planning make some tests with this tomorrow (confinament, shock sensitive, etc..).. 
thanks again!
[Editado em 27-12-2006 por Aqua_Fortis_100%]
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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12AX7
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Make a scale from some wood or metal and use standard weights (the weight of coins can be found easily). Better than 5% accuracy from little more
than trash.
Tim
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Aqua_Fortis_100%
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Tim, has you the detailed procedure (how i can do this)??
again, thanks...
[sorry about my poor english..]
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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12AX7
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Make a balance beam, put it on a pivot (a sharp corner will do) and put two scales, one on each end of said beam, equidistant from the pivot. 'Nuff
said.
If that still isn't enough, google "scale" or "balance" or something.
Tim
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Aqua_Fortis_100%
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| Quote: | originally posted by UnintentionalChaos:
Actually, one more thought. Does sodium hypochlorite do as good a job oxidizing copper as it does oxidizing iron? And if so, could I then just bypass
the H2O2 oxidation step and dissolve the oxide (I (hell, i wouldn't need all these steps if it did),II, mix?) in HCl, then proceed?
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some days ago i "surfing" on roguesci.org pages and see this:
http://www.roguesci.org/theforum/showthread.php?t=5986&h...
the result was that i turned very interested in this idea.
3CU(s) + NaClO(aq) + H2O2(aq) --> H2(g) + 3CuO(s) + NaCl(aq)
so i tried but.. didn't work!
in first attempt i put some cutted Cu wires in a big plastic descartable cup and added 50ml of household bleach and using a goggle, added slowly 100ml
of 3% hidrogen peroxide (as in the experiment "DONMAN" tried) ,the mix foamed instantaneously , but then.. NOTHING happened with the wires..
in second, i put the bleach only to cover the wires (about 10 ml) and then dropping with a eye-dropper about 30ml of the same 3%
H<sub>2</sub>O<sub>2</sub>. nothing happened..
in the 3°, i make the same of second, but let the cup aside for more than a day(the wires even seemed to be more clear!)
so, i'm irritated with this..
UnintentionalChaos, thanks for the others ideas , as soon as possible, i will buy some HCl (i used recently more than 3 L to make some NH4Cl for some
experiments)
thanks.
[Editado em 11-4-2007 por Aqua_Fortis_100%]
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woelen
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| Quote: | | 3CU(s) + NaClO(aq) + H2O2(aq) --> H2(g) + 3CuO(s) + NaCl(aq) |
This is utter nonsense. You add two oxidizers to copper wire and you really expect formation of hydrogen? If I would have seen this equation, then I
immediately was convinced of the incorrectness of the applied method and at least I would not trust the author of that page anymore as a knowledgeable
person.
But, on the other hand, I can imagine that copper is attacked by sodium hypochlorite. I even dissolved ruthenium metal in bleach, and ruthenium is
MUCH harder to dissolve than copper. I would try without the hydrogen peroxide, that only results in destruction of the bleach:
H2O2 + NaClO --> NaCl + H2O + O2 (this was the instant strong fizzling)
With bleach, a little NaOH added and heating, I expect you can make some CuO, but don't expect a smooth and fast conversion.
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not_important
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| Quote: | Originally posted by 12AX7
Make a scale from some wood or metal and use standard weights (the weight of coins can be found easily). Better than 5% accuracy from little more
than trash.
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There are bit torrents for "the golden book of chemistry" which was a late 1950s book for kids. It includes a couple of pages on making a balance in
this very fashion. Note that the weight of a US penny ha changed since the book was published.
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Aqua_Fortis_100%
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thanks woelen ..
really when i added the hydrogen peroxide in NaClO, the stuff foamed a lot , but the smell seems to me have a little chlorine or chlorine unknow
compound or vapour and ,of course the O2 as you says.. actually , i suspected before and while trying this, because i thought on interaction of gas
,solid and liquid are minimal here , and then Cu wires remain in bottom of the cup,unchanged. so your equation
H2O2 + NaClO --> NaCl + H2O + O2
is absolutelly correct.
thanks for the idea of using NaClO and some NaOH... i will try this.
(in fact,i think that this NaOH addition will not be very necessary, since most of the commercial bleachs have some in their content). again, thanks.
Edit: the equation:
| Quote: | | 3CU(s) + NaClO(aq) + H2O2(aq) --> H2(g) + 3CuO(s) + NaCl(aq) |
i retired from the link (RS forum)
[Editado em 11-4-2007 por Aqua_Fortis_100%]
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FrankRizzo
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Does anyone know the solubility of copper oxychloride in acidic water? I'm looking to separate oxychloride from a commercial fungicide which contains
both copper oxychloride and calcium carbonate. My first thought was to use HCl.
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12AX7
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Both will dissolve.
Try ammonia instead.
Tim
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FrankRizzo
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Doesn't calcium hydroxide have a very low solubility?
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12AX7
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Sure, but you have the carbonate, so that doesn't matter.
The copper tetrammine complex (hydroxide, in this case) is significantly more soluble (>10^4 times, maybe?).
Tim
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FrankRizzo
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Right, duh..sorry. Thing is, I want to preserve the copper oxychloride, not make copper oxide.
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12AX7
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I think you're SOL then.
At best, dissolve copper with ammonia (to seperate from calcium), boil off ammonia and dissolve CuO with HCl. Evaporate to a green solution, then add
base to precipitate new oxychloride.
Tim
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