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jgourlay
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Making Copper Acetate?
Gents, I've been casting about for some copper acetate to use in my continuing adventures of my son and I crystallizing everything under the sun. I
want to hit copper acetate, but am having trouble.
Either I find reagent grade at $15+ per 100g, or it's one of a bajillion ingredients in cat food and vitamins. I'm looking for the ebay grade ziplock
baggie full for $4.99.
20 years ago, I thought the chinese were going to take over the world so "speculated" in "commodities" by running out to a scrap metal dealer and
buying several hundred pounds of copper scrap. I've sold most of it, and have about 50 lbs left.
Can I get what I want by (trying) to dissolve copper in glacial acetic acid? Would that be educational for the boy? Or would it be one of those
"demonstrations" that starts with the "ooh"ing and "ah"ing and ends with the running and screaming?
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panziandi
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If you keep copper wire in acetic acid you will get a blue-green solution of copper (II) acetate. I have done this with vinegar and 33% acid, but it
is SLOW. If you heat copper wire in a blue flame you can oxidise it to copper (II) oxide which will dissolve more easily in the acetic acid. Copper
(II) oxide and copper (II) carbonate (basic) can be had cheaply and can be dissolved in the acetic acid quickly to yield the acetate. Copper (II)
acetate are beautiful crystals, enjoy 
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Mr. Wizard
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That's how I made it when I was a kid. I put some copper wire in a jar, open to the air, half full of vinegar. The vinegar does dry up, but just keep
adding to it. If I recall, the CO2 from the air plays a part in the reaction. It took weeks, but I got some of the nice crystals.
As a caution, I'd recommend gloves and a dust mask. The stuff has a nasty irritating effect on your throat when the dry powder gets in the air. Has
anyone else ever noticed this problem?
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jgourlay
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Thanks!
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Magpie
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There's some more copper acetate making experience here in this large thread:
http://sciencemadness.org/talk/viewthread.php?tid=5529&p...
[Edited on 8-9-2008 by Magpie]
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Klute
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If you have acces to nitric acid, it dissolves very easily (recycle the NOx fumes). You can then neutralize with alkali to form Cu(OH)2, heat until
all the blue gel turns to a easily-decanted black solid (CuO), decant and wash with water a few times (leave it to decant, impossible to correctly
filter), and then dissolve the CuO in 70% AcOH, and evaporate.
I've done it a few times at a 50-100g scale, because i can get nitric acid dirt cheap. Might not be the best option for everyone else.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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gsd
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You can make copper (II) Acetate by reaction of copper metal with acetic acid in presence of air (oxygen) at elevated temperature (boiling temperature
of AA). I have successfully made it as under:
take dilute (about 50%) AA in a 3 neck round bottom flask kept in a heating mantle. Fit tube filled with copper metal pieces ( small stampings,
cleaned wire scrap, turnings, tube cuttings etc. etc. - basically any small but CLEAN source of metal) on the centre neck. Attach a water cooled
reflux condensor on top of the tube. In one side neck of the RBC, insert a tube for air entry. Use 3rd neck for thermometer pocket. Attach a gas trap
to the top of condensor to scrub any escaping AA vapours.
Introduce a very small flow of air / oxygen using any suitable device ( I had used fish tank aspirator) in the flask and bring the liquid to boiling
and then to very gentle reflux.
At the refulxing temperature of AA ( about 105 Dec C) the air oxidizes the copper and the copper oxide immediately reacts with AA to form CuAc2 which
is washed down to the RBC by down coming liquid. It accumulates there and gets concentrated as the time passes. The experiment can run unattended for
considerable duration say about 8-10 hrs. Stop the heating, dismantle the tubes and pour hot CuAc2 solution in a beaker.
Beautiful Dark Green crystals of CuAc2.H2O are obtained on cooling.
good luck
gsd
[Edited on 8-9-2008 by gsd]
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Klute
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Very clever! Looks much more practical that form the oxide and cleaning it.. I will try it out next time I need Cu(OAc)2!
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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kclo4
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A few years ago I produced Copper Acetate by electrolysis of copper wires in Vinegar IIRC.
Calcium Acetate could be reacted with Copper sulfate to form Calcium Sulfate which is basically insoluble and copper acetate.
The Calcium Acetate could be produced from chalk and Vinegar. - That is with chemicals you likley have around the house.
Also, by doing it that way you could then teach your son about reactivity series, naturalization, double displacement, etc.
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chloric1
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Yeh but the calcium sulfate is a bear to filter! You need to boil with agitation for a few hours to get bigger crystals to filter.
Fellow molecular manipulator
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kclo4
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How much of a difference does boiling make?
Does it take the ultra fine calcium sulfate to something the size of table salt crystals, or something?
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ScienceSquirrel
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| Quote: | Originally posted by kclo4
How much of a difference does boiling make?
Does it take the ultra fine calcium sulfate to something the size of table salt crystals, or something? |
Boiling a precipitate can make a big difference.
A precipitate of ferrous oxalate becomes a lot more granular on boiling for a few minutes.
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watson.fawkes
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Boiling a liquid with marginally soluble solids (assuming no vapor loss) is formally similar to reflux. In reflux, a phase change of the solvent
causes part of it to go to gas, which then condenses. In boiling this mixture, a phase change of the solid causes part of it to go into solution,
when then recrystallizes.
The ultimate reason that crystals get larger is that this configuration--fewer and larger crystals--is a lower energy configuration that the prior
configuration--more and smaller crystals. The energy is, essentially, a surface tension. It doesn't seem to ordinarily act that way because the
crystals doesn't deform in response to it.
Agitation, though not like reflux, adds a second means for reducing surface area: collision.
Lastly, I would expect that putting the solution under a proper reflux column while boiling would increase crystal growth rate. An ion coming out of
solution is driven locally by supersaturation at the crystal surface. Reflux, by keeping an ever-changing part of the solvent out of commission,
increases the amount of volume with this local supersaturation property. Additionally, at the juncture where fresh solvent remixes, there's a zone of
high solubility that will tend to dissolve fines. All these dynamics are still true at low solubilities; it's just that everything works more slowly.
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kclo4
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Oh thats very interesting, thank you both for explaining that! I'll have to keep this in mind 
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crazyboy
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Add a clean copper pipe to white vinegar or better yet concentrated acetic acid, add 35% H2O2 let sit over night or boil. When bubbling ceases filter
and discard solids. Boil and collect crystals.
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itchyfruit
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copper acetate
Quote: Originally posted by kclo4  | A few years ago I produced Copper Acetate by electrolysis of copper wires in Vinegar IIRC.
I have been trying this today without much(any if i'm honest)success
My procedure: Firstly i made a couple of electrodes by curling copper wire into a flat spiral then clipped them to a small beaker i filled the beaker
to just above the spirals(40ml approx) with GAA and switched on the power(12vdc) after about an hour nothing had happened so i heated the beaker to
65oc still nothing so i added 5ml of 1mol cuso4 in the hope that this might make the solution a bit more conductive this just turned into a light blue
precipitate and sank to the bottom of the beaker(i'm guessing the GAA stole all the h2o from the cuso4,perhaps a good way to make anhydrous cuso4 ?)I
then added 10ml of 5% h2so4 the electrodes are now bubbling a bit but i don't have the deep blue solution i was hoping for!!!
Any suggestions?
Sorry i've put my post in the quote box
[Edited on 11-8-2009 by itchyfruit] |
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itchyfruit
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Now i don't know what section this has ended up in.
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itchyfruit
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Now for an update, firstly my lab stinks of vinegar
The anode(+) is coated in a green/blue insoluble looking residue the cathode(-)is covered in what must be copper and most of the cuso4 precipitate has
gone presumably onto the cathode after i added a bit more h2so4,not a good way of making copper acetate me thinks.
I also tried CU powder + GAA + 30% H2O2 this reacted quite violently and got pretty hot, but i now have a deep blue solution which i believe is copper
acetate WAHOOO
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woelen
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I made copper acetate myself from copper sulfate, sodium hydroxide and dilute acetic acid.
The procedure is as follows:
- Dissolve copper sulfate in water
- Add sodium hydroxide in excess amount, such that a blue precipitate is formed
- Heat the liquid for quite some time, until all blue precipitate has become purely black. The copper hydoxide is converted to copper(II) oxide. This
black precipitate is not so slimy as the blue copper hydroxide and can be filtered much more easily.
- Filter the black precipitate and rinse with distilled water several times to get rid of sodium and sulfate ions. Do not dry the precipitate, just
rinse it.
- Add excess 30% acetic acid to the black material and let it stand in an open vessel for many many days until it has become perfectly dry. Everything
will smell of vinegar when you do this inside, so it is best to put the vessel outside in a warm and dry place where animals and children cannot
access it. When the acetic acid is added, the liquid becomes really dark green and black material seems not to dissolve at once, but while it is
standing, slowly all of it is converted to copper(II)acetate. It is important though to have excess acetic acid.
Slowly, small crystals of copper acetate form. I obtained a crystalline meal of many glittering fine crystals. I did not get a nice single crystal,
but you might obtain bigger crystal if you redissolve it in a lot of very dilute vinegar and let it evaporate very slowly.
The picture below shows the final result of this experiment. This is approximately 10 grams of copper(II)acetate.
[Edited on 12-8-09 by woelen]
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itchyfruit
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Thanks, I'll give it a try(i used a similar process to make cuprous chloride) i'll have to use koh as my naoh is not very pure.
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kmno4
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In making Cu(OAc)2 it is important to to use excess of acetic acid - as woelen said. In another case you will get basic copper acetate, colored
green.
Pure Cu(OAc)2 hydrate is colored deeply blue and when hydrolysis took place, colour changes to green-blue.
The best way to obtain pure crystals is evaporation of water from saturated solution at room temp. Unfortunately it is very slow and not effective
(saturated sol. at r.t. is only 7g of acetate per 100g water). My Cu(OAc)2 is green-blue, because I had no time for playing in this way. I used CuO
(contaminated with Fe and Zn, total ~5%) and acetic acid on boiling.
Prepared acetate was recrystallized from hot water and acetic acid. Analysed with x-ray spectrometer it has shown 99%+ of Cu.
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itchyfruit
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I'm just of to try this now,so by excess(try not to poke fun at my lack of knowledge'entropy51'i'm looking a you  ) you mean for example 100ml of 1mol cuso4 + 110ml of 1mol koh this would be a slight excess of koh is that correct?
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entropy51
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Surely even you can succeed with one of the recipes graciously posted for you.
But you'll probably drop it in the sink when you're finished.
Don't forget that KOH out of the bottle is usually quite a bit less than 100% pure. And NaOH is usually cheaper.
You might want to look up "peracetic acid". You're a strong contender for the Darwin Award.
[Edited on 12-8-2009 by entropy51]
[Edited on 12-8-2009 by entropy51]
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bfesser
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I'm not exactly sure what entropy51 is talking about here, but please, don't dump copper waste down the drain. It's particularly harmful to marine
environments. Just reduce it to the metal, or precipitate it as a salt, filter it, and keep it. Waste not, want not.
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kmno4
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| Quote: Originally posted by bfesser | | ... please, don't dump copper waste down the drain. It's particularly harmful to marine environments. Just reduce it to the metal, or precipitate it
as a salt, filter it, and keep it. Waste not, want not. |
Marine environments in the drain ?
From 10g or even 1kg of copper salts to environmental pollution is very long way. Especially the way leading via the drain ....
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