people
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How to make CuO from Cu??????
can somebody help me????
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ordenblitz
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It's pretty simple.
Expose copper powder to air, and wait a while.
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JohnWW
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Takes a MUCH TOO long time! And besides, CuO tends to absorb CO2 to make malachite, CuCO3, which is the green patina on copper-roofed buildings.
John W.
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vulture
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Copper.
Bunsenburner or hot air gun.
Full blast.
Done.
Sjeez.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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hodges
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You could try electrolysis using copper electrodes in a solution of table salt and water. You should get copper hydroxide precipitate. Wash this
precipitate and then dry in the oven and you've got CuO.
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The_Davster
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1. Disslove in nitric acid
2. Once dissolved heat the solution to boiling and add the stoichiometric ammount of solid NaOH necessary
3. Filter out the black solid produced and wash and dry it, this is CuO
I have made CuO like this many times except I started from copper sulfate.
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ordenblitz
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Quote
------------------------------------------------------------------------
Takes a MUCH TOO long time! And besides, CuO tends
to absorb CO2 to make malachite…
------------------------------------------------------------------------
That’s interesting since the company I buy CuO from, American Chemet Co. (a very large manufacturer by the way) told me directly that their
production method for CuO was to expose copper powder, -325 mesh, to the atmosphere for a period of time. That was the technical description….
The simple description was, leave the barrel bands off the lids of 30 gal drums of Cu powder for a couple of months.
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JohnWW
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Any CuO produced simply by atmospheric oxidation at ordinary temperatures of Cu powder would, at best, be of only "technical" quality, not
laboratory reagent quality, because of the absorption of CO2 from the atmosphere by CuO in the presence of moisture, resulting in malachite, CuCO3, or
its basic variety found in nature as the crystalline mineral, (CuOH)2CO3. This is the pale green chalky substance seen on old copper roofs.
Besides, because of the slowness of oxidation of bulk Cu powder, in a barrel from which the lid has been removed, on exposure to air, there is bound
to be a lot of unoxidized Cu, or Cu2O, in the product, especially at the bottom of the barrel.
This "technical copper oxide" would therefore be quite unsuitable as a quantitative reagent, and would be fit only for dissolution in acids
to produce Cu salts in solution (in which situation any Cu(I) would be oxidized to Cu(II)), which could then be either used as industrial chemicals
(in which the Cu concentration would have to be analysed and adjusted if necessary) or purified by crystallization.
John W.
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Marvin
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Its surprising, but not difficult to bilieve.
325 mesh is very fine copper, and the avarage particle size could be in the region of 10microns. I dont know how fast it would react with oxygen,
but that is a really fine powder and a massive surface area.
My understanding of copper oxide is that it wont react with carbon dioxide. Maybe if it was partially submerged in water, but I would need to be
convinced. Oxygen itself is about 1/5th of the air, but carbon dioxide makes up, and Ive had to look this up, only 0.03% of air. To form significant
carbonate compaired to oxide youd have to have a high air flow which simply removing the bands would not get you and the carbonate forming reaction
would need to be fast and it certainly isnt that. In comparison, with damp air clean copper form a black tarnish quite rapidly. I wonder how hot the
drums get during the first few days.
Malachite forms typically when copper sulphide ores meet carbonates, typically neer volcanic activity, by weathering of copper ores and other wet
processes.
If nothing else I have copper pipes in my bathroom that seem to be covered in a black oxide layer, not a green carbonate layer, and they've been
exposed to damp air for 40 years.
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I am a fish
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Formation of hydroxides and carbonates is unproblematic, as they both readily decompose into the oxide when heated.
Before starting, you should weigh the copper, so that afterwards, you can tell if the reaction has gone to completion. 1kg of Cu should yield
1.252kg of CuO (after heating to drive off all H2O and CO2). If the mass of the the product is less than this, there is still some elemental Cu
remaining.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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JohnWW
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Examples of old copper roofs which have developed a chalky pale green patina of malachite due to exposure to atmospheric H2O, O2 and CO2 for many
years: the dome of the Law Courts Building in Dublin, Ireland; the Statue Of Liberty in New York, N.Y.; Chartres Cathedral in Chartres, France; the
Karlskirche in Vienna, Austria. I have photographs of them.
John W.
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ordenblitz
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Marvin said:
-------------------------------------------------------
I wonder how hot the drums get during
the first few days.
-------------------------------------------------------
I don't know how warm it gets, but the man said that they leave the drum lids on but take the bands off. That must regulate somewhat how much air
is getting to the copper to slow the reaction down.
American Chemet, here in Montana, is quite a big producer and their quality is excellent. I would imagine if this method didn't work they would
certainly change their process.
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Marvin
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John,
You seem to be confusing malachite, the mineral, with Verdigris, which by definiition is the blue/green corrosion product of copper. This is mostly
basic copper sulphates (and optionally basic copper chlorides around coastal areas). The statue of liberty is a good example.
http://www.mail-archive.com/word@tlk-lists.com/msg00023.html
It forms very slowly and almost not at all in low sulphur or low rainfall areas. Formation is dependant on prolonged contact with rainwater.
http://www.paradigmshingles.com/weathering.html
There would be no liquid water in contact with the copper powder so I do not see production of any of these compounds as significant.
We will of course inform them that should they leave the lid off, let rainwater in and alow contact with the air for a decade or more the copper oxide
may end up contaminated with unwanted products - and we will site several buildings over a century old as examples. Doubtless they will disbilieve
everything we say ignoring all taught chemistry and demand hard evidence - but its ok! You have some pictures. Keep them safe, they may be vital some
day.
[Edited on 22-9-2004 by Marvin]
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JohnWW
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Marvin:
The only problem with your verdigris theory - basic Cu sulfate, rather than carbonate - is that those copper-roofed building examples that I
mentioned, and others that could easily be found, are nearly all so old (with the possible exception of the Statue Of Liberty), some dating from about
1200, that they received their green patinas well BEFORE industrial-scale coal-burning resulted in any significant SO2 and SO3 (from sulfur in poorer
grades of coal) being released into the atmosphere.
However, with the advent of significant "acid rain" in the 20th century, due to release of sulfur oxides from industrial areas, it is quite
likely that the most recently added layers of such green patinas would have a significant proportion of CuSO4, or basic Cu sulfate, in them,
displacing some of the carbonate. But bear in mind that CuSO4 is readily water-soluble, while CuCO3 and (CuOH)2CO3 are not, so the sulfate would be
easily leached out by heavy rain.
Besides, "verdigris" seems to mean either Cu acetate (or basic acetate), or any greenish superficial corrosion product of Cu, bronze, or
brass, regardless of composition.
To get back to the topic of this thread: the presence of significant SO2 and SO3 in the air in industrial areas where S-containing coal or oil is
burned (but most modern oil-refining uses hydrodesulfurizers and other means to remove the S, present mainly as thiophene and its derivatives) means
that the method described for producing industrial-grade "Cu oxide", viz. atmospheric oxidation of fine Cu powder in barrels in industrial
areas, would also contain some sulfate as a contaminant, as well as carbonate. This would provide problems if the product, after dissolution with
common strong acids other than sulfuric acid, was used in industrial reactions in which Ca, Sr or Ba are also present; these would be precipitated as
the slightly-soluble to insoluble sulfates.
John W.
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Texium
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