Sciencemadness Discussion Board - Copper acetate and acetone?

Copper acetate and acetone?

bigtrevs98 - 3-5-2015 at 22:50

So I have a solution of copper acetate and water. I put 50 mL of acetone and 10 mL of Copper acetate solution into a container. The copper acetate goes from see-through to a dense looking whitish liquid..Also around the top of the clear liquid there seems to be a rapid precipitation of water or something. What happened to the copper acetate?

So I collected some of the precipitating clear liquid on the cup. Its acetone I think. It smells/burns like acetone. But it precipitates a lot quicker than when I first made the solution

[Edited on 4-5-2015 by bigtrevs98]

violet sin - 4-5-2015 at 00:01

Copper(I) acetate perhaps? Found this after googling copper acetate solubility in acetone.
-- https://books.google.com/books?id=Zk0z22smWUoC&pg=PA80&a... ---

Handbook of copper compounds and applications
"Made by Reducing an ammonia solution of copper (II) acetate. on acidification, white crystals of copper (I) acetate precipitates"
*edited for wrong name of book,... lack of sleep

[Edited on 4-5-2015 by violet sin]

bigtrevs98 - 4-5-2015 at 06:48

Just a little update. The whitish substance seems to be getting smaller and smaller. And could someone explain the difference and uses between the two? (Copper(ii) acetate and copper(I) acetate)

[Edited on 4-5-2015 by bigtrevs98]

blogfast25 - 4-5-2015 at 08:40

Quote: Originally posted by violet sin

Copper(I) acetate perhaps? Found this after googling copper acetate solubility in acetone.
-- https://books.google.com/books?id=Zk0z22smWUoC&pg=PA80&a... ---

So where's the reducing agent, violet sin? Oxidising acetone in these conditions is nigh impossible.

Acc. your own source Cu(II) acetate is only poorly soluble in acetone. Most likely then the acetone acted as an anti-solvent, precipitating the Cu(II) acetate.

That some of the Cu(II) acetate seems to have re-dissolved could be due to better mixing of the water and the acetone.

DrMario - 4-5-2015 at 09:30

I'll try to reproduce this. I have a tiny amount of cupric acetate that I could partially sacrifice for the sake of science.

EDIT: I used a very diluted solution of cupric acetate in water. Added an equivalent volume of acetone, and indeed, I see the liquid becoming slightly opaque.

I might try with a more concentrated solution later. Too bad I have so little cupric acetate.

[Edited on 4-5-2015 by DrMario]

Pumukli - 4-5-2015 at 09:35

You mixed copper acetate SOLUTION with acetone, so the starting material surely contained water. Copper(2+) ions in water have a nice blue color. When you mixed this blue solution with acetone (which is almost free from water if pure) the acetone acted as an "anti solvent" as blogfast said, because the solubility of copper acetate in aceton is much lower than in water I bet.
Aceton sort of "dehydrated" the previously water solvated copper (and acetate) ions and due to the poor solubility in that solvent solid, whiteish, copper acetate fall out from the solution.
It was white, because the crystals were grown in a low water content environment (fairly concentrated acetone). I think anhydrous copper acetate has a very faint blue color, or straight white, similarly to anhydrous copper sulfate.
Later part of the precipitate redissolved probably because of thorough mixing of acetone and water - as blogfast wrote.

MKSStal - 4-5-2015 at 09:52

Adding acetone or some similar organic solvent is a popular way to participate some ionic, water solluble salt. Some time ago i used that to participate lead(II) acetate from its water solution by adding isopropyl alcohol. Firstly i thought I had achieved my goal- white, crystalline mass was on the bottom. However after filtering and drying it my yield was maybe about 60% (really not remember). Also after adding KI solution to filtered solution much of yellow lead iodide was formed. As Cu(AcO)2 is quite similar to Pb(AcO)2 the same think was done by You. A participate is copper acetate and due to its not too bad solubility in acetone/ water mixture some of it is still in solution making it blue. In my case solution was colourless as lead acetate water solution is. In my opinion its caused by similarity between acetate ions and simple organic solvants. In your case [CH3CO]O- and [CH3CO]CH3. Of course salts are ionic so the solubility is limited.

violet sin - 4-5-2015 at 11:34

"So where's the reducing agent, violet sin? Oxidising acetone in these conditions is nigh impossible.

Acc. your own source Cu(II) acetate is only poorly soluble in acetone. Most likely then the acetone acted as an anti-solvent, precipitating the Cu(II) acetate."

@ blogfast25: I don't believe I implied any kind of reaction occurred by simply adding acetone,... My statement was " copper (I) acetate perhaps?" Followed by a brief description from the reading I found because Google books doesn't alwayse hold your page number when linked. And I was working from my phone. In other words I didn't mean to imply a reason, just a candidate.

Absolute alcohols and water free(or nearly) acetone are commonly used as "crashing" agents to precipitate crystals that would decompose from the heat or extended exposure to atmospheric conditions while trying to drive off the water. Seen all over YouTube, and mentioned by more skilled users on SM as well. The mechanism is pretty straight forward.

As always I was only trying to be helpfull with the limited time I have to participate here between work, family and sleep time... Not a know-it-all master chemist... (Which I never do). This guy hasent had enough time with the books in probably,.. about 16 months, to make an authoritative statement of facts. Basically since my son was born. As evidenced by my minor/lacklustre comments here and there for some time now. I surely enjoy reading on site, and helping with pointing to auxiliary reading from elsewhere on the web. The book "handbook of copper compounds and applications" seemed like a nice dirrection to go looking for answers...

This isn't a lashback, just a simple explanation...
-Violet Sin-

[Edited on 5-5-2015 by violet sin]

DraconicAcid - 4-5-2015 at 11:59

While I can see acetone crashing out the copper(II) acetate, I would be very surprised if the product was anhydrous. And acetone will not reduce the copper(II) to copper(I) (soluble copper(I) salts being very water-sensitive). I wonder if it's hydrolyzing, and precipitating a basic copper(II) acetate, or if the precipitate just looks white because the crystal size is very small.

Loptr - 4-5-2015 at 12:25

bigtrevs98, have you collected any of the white precipitate and allowed it to dry?

bigtrevs98 - 4-5-2015 at 15:20

Thank you ALL regardless of if you were helpful or not you took the time out of your day to try to help me and I greatly appreciate everything that may be of any type ofhelp (and what isn't) and yes loptr. But it all dissolved away before I could dry it out. Maybe run it through a filter? I'll make it on a bigger scale and see what I can get. I'll keep you all updated.

[Edited on 4-5-2015 by bigtrevs98]

Oh and another quick question. In experimenting with the clear top-layer (smells like acetone on steroids and has a blue color to it) I mixed some of that with household bleach and the solution precipitated black/brown specks that floated on top and eventually settled to the bottom and seemed to harden a bit.. I know mixing bleach and acetone make chloroform. But I think the brown/black specks may have been dissolved by the chloroform because isn't chloroform. Solvent? But original question was what are the specks? (I'll upload pictures in a couple minutes

[Edited on 4-5-2015 by bigtrevs98]

[Edited on 4-5-2015 by bigtrevs98]

blogfast25 - 4-5-2015 at 15:44

Quote: Originally posted by bigtrevs98

Oh and another quick question. In experimenting with the clear top-layer (smells like acetone on steroids and has a blue color to it) I mixed some of that with household bleach and the solution precipitated black/brown specks that floated on top and eventually settled to the bottom and seemed to harden a bit.. I know mixing bleach and acetone make chloroform. But I think the brown/black specks may have been dissolved by the chloroform because isn't chloroform. Solvent? But original question was what are the specks? (I'll upload pictures in a couple minutes

You really shouldn't be mixing stuff just willy-nilly, you know?

Chloroform is a solvent but it doesn't form that easily in your conditions. It's also not a solvent for ionic compounds like Cu(II) acetate.

If there was any heat involved, the black specs were probably partly dehydrated copper hydroxide. Bleach is quite alkaline and precipitates Cu(OH)2 from Cu(II) salt solutions.

bigtrevs98 - 4-5-2015 at 15:50

Yeah I know blogfast. Its not really a good idea. I usually do things in very small pre portions first. (Couple drops) I've only partially been through a chemistry class but I know the safety precautions. I do most of my experiments outside too. I just do things with some knowledge I usually try to find out as much info as I can first also. Like I know not to mix H2O2 and acetone unless I actually know what exactly I'm doing first. I'm hoping to start college in next few months. But I try to just learn and expand my mind with the small am mount of supplies I have available at the moment.

[Edited on 4-5-2015 by bigtrevs98]