Draeger
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Getting rid of acetic acid in copper acetate solution?
I made some copper acetate. Problem is that there's still some acetic acid in solution. I don't have any sort of ventilation so boiling it is not an
option. Is there any other way I could get rid of it?
Collected elements:
Al, Cu, Ga, C (coal), S, Zn, Na
Collected compounds:
Inorganic:
NaOH; NaHCO3; MnCl2; MnCO3; CuSO4; FeSO4; aq. 30-33% HCl; aq. NaClO; aq. 9,5% ammonia; aq. 94-96% H2SO4; aq. 3% H2O2
Organic:
citric acid, sodium acetate, sodium citrate, petroleum, mineral oil
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UC235
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What's the end goal here? It crystallizes just fine from solution with an excess of acetic acid. In fact, it's probably preferred so as not to get
basic copper acetate.
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Draeger
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Quote: Originally posted by UC235  | | What's the end goal here? It crystallizes just fine from solution with an excess of acetic acid. In fact, it's probably preferred so as not to get
basic copper acetate. |
Can't crystallize most of the product without concentrating the solution, as far as I know at least, and to concentrate it I'd have to boil it, which
I can't since the smell would likely be unbearable because I have no ventilation. I could also wait for it to evaporate, but that would take a long
time, so I am looking for a different way to get rid of the acetic acid, provided it exists.
Collected elements:
Al, Cu, Ga, C (coal), S, Zn, Na
Collected compounds:
Inorganic:
NaOH; NaHCO3; MnCl2; MnCO3; CuSO4; FeSO4; aq. 30-33% HCl; aq. NaClO; aq. 9,5% ammonia; aq. 94-96% H2SO4; aq. 3% H2O2
Organic:
citric acid, sodium acetate, sodium citrate, petroleum, mineral oil
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Ubya
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i also had your issue, i overestimated the amount of acid i needed so instead of wasting the excess acid (cheap for many but i made this myself, i was
emotionally involved) i added more copper and instead of using H2O2 (i only have 3%, the volume would have been excessive) i used a ceramic airstone
and a small air pump on the lowest setting to oxidize the copper in solution (it took maybe 2 days).
Lucky for me the solution got to saturation and i begun seeing copper acetate crystals growing, soi just filtered the copper metal and evaporated the
solution (without boiling) for an evening unitil i got my powder 
if this is not an option for you, maybe solvent extraction can work as acetic acid is a weak acid. you could try with a non miscible alcohol or maybe
ethylacetate (more apolar solvents could be used but i'm not sure about their efficacy)
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Bedlasky
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What acid you used? GAA or vinegar? If you have excess of vinegar or only slightly excess of GAA, just boil it down with open window. People normally
boils infusions containing lots of vinegar. Yes, it smells horrible but it can be done inside.
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woelen
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It really is important to crystallize the copper acetate from the acidic solution, otherwise you will get basic copper acetate. Copper acetate tends
to hydrolyse in water and forms insoluble compounds. If a little acid is present, then this hydrolysis does not occur.
I myself made copper propionate recently in a similar way (from unknown eBay-quality CuO and high grade propionic acid) and I just let the solution
evaporate slowly, in our garden shed. There was a strong smell of propionic acid in the shed (it smells much like vinegar, albeit a little more
musky), that's why I did not do this inside. The vapor is not really toxic (just like acetic acid vapor is not toxic), but having that smell inside
is not fun. It took more than a week, before solid crystalline material settled at the bottom. I also did not allow all of the liquid to evaporate to
dryness, when 90% or so was gone, I decanted the remaining part and press-dried the crystals in filter paper (coffee filter with tissue wrapped around
it) and then allowed the crystals to dry. Impurioties remain mostly dissolved in the liquid and by sacificing 10% or so of your yield you end up with
a much purer product.
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Chemorg42
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According to wikipedia, sodium acetate has a solubility of about 32 g / 100 mL in cold water, while copper (II) acetate has a solubility of about 7 g
/ 100 mL in cold water. Therefore, couldn't you just neutralize the acid with sodium bicarbonate, then boil off the excess liquid, and finally chill
the solution to cause most of the dark green copper acetate to crash out of solution?
Others have said that you want a somewhat acidic environment, so maybe this is not the best option, though I think it would theoretically work.
Anyone who is not shocked by quantum theory has not understood a single word. (attributed to Niels Bohr)
I think I can safely say that nobody understands quantum mechanics. (Richard Feynman)
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DraconicAcid
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| Quote: Originally posted by Chemorg42 | According to wikipedia, sodium acetate has a solubility of about 32 g / 100 mL in cold water, while copper (II) acetate has a solubility of about 7 g
/ 100 mL in cold water. Therefore, couldn't you just neutralize the acid with sodium bicarbonate, then boil off the excess liquid, and finally chill
the solution to cause most of the dark green copper acetate to crash out of solution?
Others have said that you want a somewhat acidic environment, so maybe this is not the best option, though I think it would theoretically work.
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Mo, that won't work at all- you'll precipitate basic copper acetate.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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unionised
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It won't really work- because you will precipitate basic acetates when you crystallize it but... if you insist.
Take a little of the solution (maybe 5 or 10%) and add an excess of sodium bicarbonate to it in a separate container.
That will give you a precipitate of copper carbonate.
Filter that off and wash it with water.
Then add the clean copper carbonate to the remaining copper acetate / acetic acid solution and leave it to react with the acid.
hat should get rid of the smell of acetic acid.
But I still think you will get poor crystals when you let the water evaporate.
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RogueRose
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I would also really suggest crystalizing with an excess acid and the acetate does the best with slow evaporation. If you don't need it ASAP then just
let it sit out and forget about it for awhile. If you want to make it go a little faster, put a fan to blow across it and it should speed it up by
2-6x faster (depends on the humidity where you are).
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