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Waffles SS
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Copper(II) Hydroxide !
Today i decided to make Copper (II) hydoxide but i got amazing result.
First i put some copper wire into plastic baker and then add nitric acid(55%)(i used fuming hood) brow somke start to envolved(No2) and i got blue
solution(Copper nitate solution)
after that i add sodium hydroxide solution to baker and i got dark precipitate!! i think i should get blue precipitate not dark!
Cu + 4HNO3 = Cu(NO3)2 +2 NO2 +2 H2O
Cu(NO3)2 +2 NaOH = Cu(OH)2 + 2NaNO3
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trb456
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Perhaps too much HNO3? I have a textbook copy of this very experiment that warns to NOT use an excess of HNO3. Either that or your solution is hot,
because it sounds like you got copper oxide (brown/black precipitate):
Cu(OH)2 + Δ ─› CuO + H2O
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Mixell
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Copper hydroxide decomposes to copper oxide (CuO) at 80C.
So I assume you added the hydroxide solution to the copper solution while it was still hot, or you dissolved the sodium hydroxide in water and added
it immediately to the copper solution.
Excess of nitric acid will just react with the sodium hydroxide and dissolve any copper hydroxide that will form, you will end up with a solution of
sodium and copper nitrate (and nitric acid if the amounts weren't stoichiometric with excess of HNO3).
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bbartlog
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I think decomposition begins at even lower temperatures, at least in aqueous solution. Keep everything cold.
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Waffles SS
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Yes, i think most of my copper hydroxide decompose to copper oxide(because the temperature increased to 90c !)
The biggest problem is Nitrogen dioxide. it is highly toxic and lot of it produce in this reaction,next time i want to lead it to concentrated sodium
hydroxide solution(sodium nitrite and nitrate will produce)
In other hand copper(II) oxide reacts with concentrated alkali to form the cuprate salts:
2 NaOH + CuO + H2O → Na2[Cu(OH)4]
This mean more sodium hydroxide convert copper oxide
I am looking for better method for make copper hydroxide but unfortunately cooper react very well just with nitric acid. 
Anyone has better idea?
[Edited on 17-4-2011 by Waffles SS]
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trb456
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Got any copper sulfate?
CuSO4 + 2NaOH -> Cu(OH)2 + Na2SO4
If you have sulfuric acid, react with copper (requires electrolysis--forgot this the first time):
Cu + H2SO4 -> CuSO4 + H2
Or, use your copper oxide (no electrolysis)!
CuO + H2SO4 -> CuSO4 + H2O
[Edited on 17-4-2011 by trb456]
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woelen
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You also can work with the copper nitrate, even when excess acid is present.
You need to dilute the solutions and keep them cold. The reaction between excess acid and NaOH is very exothermic and the heat produced in that
reaction is enough to decompose Cu(OH)2 to CuO and water. So, dilute your solution to 1/10 of its original volume with cold water and do the same with
the NaOH. When you do that, then you'll obtain a blue precipitate. Stir the solution to assure that all of the copper ions react. Add so much NaOH,
such that a sample of the liquid after stirring is just slightly basic (e.g. just red to phenolphtalein). Allow the precipitate to settle and decant
the solution above it. This should be colorless. The colorless solution may be flushed down the drain, it contains very little copper.
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Arthur Dent
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Not necessarily. As per our fellow member Nurdrage's video, you can also use a dilute solution of sulfuric acid with a bit of nitric acid as oxidizer
and you'll end up with a good yield of Copper Sulphate solution. His recipe is 30 ml of water, 5ml of
H<sub>2</sub>SO<sub>4</sub> and 3 ml of HNO<sub>3</sub> and an excess of metallic copper.
I've literally made 100 g of Copper Sulphate with plain telephone wire (adjust the ratio according to your requirements). it's a quick reaction too,
after an hour or so when the copper no longer fizzes and the solution is intensely blue, heat the solution a bit and when it has reduced by about
half, cool it down and watch the beautiful crystals forming!
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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Mixell
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Hydrogen peroxide and any mineral acid will do the trick, although using nitric acid is a lot cheaper.
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Waffles SS
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I think H2O2 as oxidizer is safer that Nitric acid because it wont make Deadly,nasty,... NO2(my friend damaged by NO2)
Cu + H2O2 + H2SO4 = CuSO4 +2H2O
(Cu + H2O2 = CuO + H2O
CuO + H2SO4= CuSO4 + H2O)
and then:
CuSO4 + NaOH = Cu(OH)2 + NaSO4
I want to try this method and i want to test reaction of copper with sodium hypochlorite
[Edited on 18-4-2011 by Waffles SS]
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Mixell
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Just one thing, H2O2 is very prone to decomposition, and most of it decomposes in the process.
I made CuCl2 using hydrochloric acid and hydrogen peroxide, I ended up using a nice amount of my 33% hydrogen peroxide (about 2-4 times more than the
stoichiometric amount needed for the reaction).
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woelen
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H2O2 as oxidizer is not fine if you want to make Cu(OH)2, unless you can be sure that no excess H2O2 is present anymore when the NaOH is added to
precipitate the copper(II). Even a slight excess of H2O2 leads to formation of a brown precipitate, which is a mix of copper(II)hydroxide and some
peroxo complex of copper(II).
Just as a test, try this:
Dissolve some CuSO4.5H2O in water.
Add some solution of NaOH.
Repeat the same experiment, but now add some H2O2 to the solution of CuSO4.5H2O and then add the solution of NaOH. You'll see a brown/black
precipitate.
A nice thing is to add some H2O2 to the blue precipitate of Cu(OH)2. You then see that the precipitate turns dark.
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MrHomeScientist
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I've noticed copper(II) hydroxide's instability myself, too. I tried to make some using the CuSO4 + NaOH method, and I got a very thick, turquoise
blue precipitate which looked great. I don't have a vacuum filter, so I used gravity filtration and let it dry. This was a mistake because the
precipitate was so thick it stayed wet, and it all decomposed into black CuO.
Sounds like next time I should chill everything down and buy a vacuum filtration setup for best results.
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Waffles SS
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I tried another method today but result wasnt great
First i add some copper metal to solution of 95%sulfuric acid and 50%H2O2(1:1) after 2-3 minutes vigorous reacton start and i lost all of my H2O2 and
then i add more H2O2.(this method need lot of hydrogen peroxide)
When i ensured that all of my H2O2 is decoposed then i add cold sodium hydroxide solution and got blue precipitate(Cu(OH)2)
Next time I decide to use aquarium pump replacement for hydrogen peroxide. I think aqurium pump can provide enough oxygen for oxidize copper to copper
oxide
2Cu + O2 = 2CuO
CuO + H2SO4 = CuSO4 + H2O
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Poppy
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copper oxide Rage
That was caused because your copper hydroxide was still wet so bearing the formula CuO.H2O or perhaps Cu(OH)2.H2O which makes it prone to dehydrating.
If you stand the hydroxide decanting for a long period of time it will vanish its water of hydration and will be considered "dry" even dumped into
water.
This was particularly frustating for me since I could no longer produce the oxide even at 95° C elsius high.
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violet sin
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electro chem? EASY  epsom salt solution + copper electrodes (one electrode at
top + one at bottom of solution with a plastic sleeve) + electricity = Cu(OH2) blue gel ppt.
really easy to set up and monitor regularly. not so easy to gravity filter Cu(OH)2, much like Ni(OH)2 texture, but blue. even harder to rinse unless
you wanted to decant a bunch of times or have a vac. saw it a few times on you tube, mine was contaminated with Mg(OH)2. came out as a fine whit
powder mixed with the black copper oxide after heating.
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White Yeti
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My experience with copper hydroxide is that it's a royal pain to gravity-filter, in fact I strongly recommend against it. I finally resorted to using
paper towels to siphon off the entrapped liquids because it was taking so long. It was a big mess and a big waste. Even at room temperature copper
hydroxide will dehydrate to copper oxide, so unless you have a good use for it, it's not worth making it in large quantities.
"Ja, Kalzium, das ist alles!" -Otto Loewi
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Manifest
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How would this work out?
I would of thought the copper wouldn't displace the sodium.
I'm probably wrong...
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violet sin
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it doesn't turn to the oxide unless you heat it. I have had like 1/3 of a gallon milk jug full of pretty blue paste for well over 11 months and not a
single black speck in it. only when I put it on the stove did it change. I have been decanting and changing the water in an attempt to "wash" it.
don't need it right now so not a prob for me. easy peasy.
from what I remember the electrolysis of the MgSO4 solution sends the Mg+2 over and tries to reduce it, but because of its activity it just oxidizes
the copper electrode and stays in solution as Mg+2. starts churning out lots of blue flocculant ppt. that eventually settles.
and YES IT IS A FREAKING PAIN to filter. and I also tried to wick the moisture out with a draping towel but the epsom salt dried on the paper and it
stopped leaching out. though I did find that if you got it settled and decanted, put the blue paste in a few paper towels inside a regular dish towel,
that you could squeeze out the water by twisting it. don't try it with just the paper though cause it will pop through and go all over your stove and
on you running burner... oh wait that was just me lol. learning curve. also I imagine you could easily pour it into a water bottle and cut/drill 1
or more holes in the lid, then put paper towel or cloth inside the cap. screw the cap back on, hold it upside down and squeeze... water will go out
like it was under pressure cause it is.
there is more than enough to go on floating around youtube. and shoot your power supply could easily be an appropriate DC transformer from what ever.
ya know the black box with a cord like thing that plugs into the wall and then into some printers, walk man, stereo, what ever. a thrift store here
has a few baskets of em for 50cents each. I did all my experiments with a hacked ATX computer power supply( upgraded my PC) but any way I ran on
12V rail. so any of the lill transformers around 12V and I don't know maybe 1 amp or so if you can source one. 500mv would still work just slower,
but SOOOO easy. just don't use one that you want b/c they don't like the load of a Cu(OH)2 cell as much as the device they were made for and some
crap out quick.
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White Yeti
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I've done electrolysis before, but I've always been limited by the capacity of my power supply. Sodium carbonate is a good electrolyte as far as I
have seen. The important thing to remember is to use an electrolyte whose anion will not get oxidized at the anode, carbonate is very stable all
things considered, so is sulphate. Chloride, for example is not, it will oxidize to free chlorine and hypochlorite, and an electrolysis will produce a
motley of products.
I'm not the only one who has seen this decomposition:
http://www.youtube.com/watch?v=nDP3ShdbC5k
My goal is to make copper oxide anyway, so this is actually doesn't matter too much.
"Ja, Kalzium, das ist alles!" -Otto Loewi
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ElectroWin
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I seem to recall slowly adding sodium bicarbonate into copper sulfate solution and getting lovely blue copper hydroxide (and lots of bubbles!)
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White Yeti
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No, the precipitate would be copper carbonate. Same colour, different texture, much more stable, and easier to filter than copper hydroxide.
Decomposition of copper carbonate takes place at around 150C.
"Ja, Kalzium, das ist alles!" -Otto Loewi
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violet sin
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ya I was going for CuO also. wanted to play with flame color and try some fast thermite but leaching out all the epsom was a problem.. less than desired speed w/ thermite. still had fun, though I wasn't able to get the
sodium carbonate to do much. I also had read that it was a decent alternative to epsom and easier to deal with, but my cell/PSU said NO! prob should
have acid etched my older electrodes first. but any way it didn't conduct. I didn't wanna spend 20$ on a pound of Cu Sulfate to make the oxide when
I collect copper metal from my jobsites.. piles of copper everywhere. soo electrolysis was easiest route for me. only cost was time and a lill
electricity
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White Yeti
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I think it's easier to turn copper sulphate to oxide. I find that making copper oxide by electrolysis is a real hassle, and I would much rather take a
pound of copper sulphate, mix with an equivalent amount of sodium carbonate and filter off the carbonate. There is no better or best way, there's just
what you're willing to do to make it work. I can't obtain copper sulphate, so I have to make the acetate myself instead. That in and of itself is a
hassle.
"Ja, Kalzium, das ist alles!" -Otto Loewi
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violet sin
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ya I hear ya, thats what I like about this forum. people all trying to get to the same point, but many circumstances and starting materials are
different for each. it helps round out the knowledge base coming at it from all sides if you ask me. good stuff. hope my input helped a bit.
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