Sciencemadness Discussion Board

crazy foam while synthesizing copper (II) acetate

kronos - 21-2-2015 at 10:05

Like everyone i also want to make a beautiful collection of colourfull copper compounds.. in India we have a very limted access to very limited number of OTC reagents.. So i got some food grade vineger, Copper wires and 20volume hydrogen peroxide(6%).. And mixed equal volumes of vineger and hydrogen peroxide and dumped a good amount of copper wires.. After 1hr saw the container in which i was making the compound was overflowing with a strange thick foam which was totally determined not to go away, the top of the foam was brown but the rest was white:mad:.. After dumping the foam somehow though i found the solution to be black instead of a beautiful blue.. Sad.. I cannot guess at all what is going on here... Please help me out.. :o :(

Zombie - 21-2-2015 at 10:18

Distilled White Vinegar or some other sort?

kronos - 21-2-2015 at 10:26

Distilled white vineger yes...5% concentration

Molecular Manipulations - 21-2-2015 at 10:47

A lot of times they distill vinegar and then add sugars to it afterward, but they still call it distilled. Evaporate a few mLs of your vinegar and see if there's any solids left.
I'm guessing some organic got oxidized by your peroxide and the foam is mostly carbon dioxide and catalyticly released oxygen.

[Edited on 21-2-2015 by Molecular Manipulations]

kronos - 21-2-2015 at 23:30

Okay thanx for the advice... I will try evaporating a bit and ghen i will post the results.. :)

kronos - 21-2-2015 at 23:53

okay.. I just evaporated half a cup of my said distilled white vineger... And there was no residue left at all at the bottom of my container.. Now what ahould i do

Molecular Manipulations - 22-2-2015 at 00:06

Actually it appears I was partially wrong. While sugars are sometimes added to "distilled" vinegar, apparently it's not even distilled in the first place. From Wikipedia:
Quote:

The term "distilled vinegar" is something of a misnomer, because it is not produced by distillation but by fermentation of distilled alcohol

Thus the list of volatile impurities is longer than I thought.
So even if your vinegar has no added solids doesn't mean it has no other impurities. If you can distill it, I'd try that. Otherwise try another brand.

kronos - 22-2-2015 at 01:51

Okay.. Thanks a lot.. After thinking about what you said... I remembered that previously this thing did not happen with the brand i used earlier.. So I think I need revert back to that brand:D...

blogfast25 - 22-2-2015 at 05:10

The black may be due to a mixed valence compound Cu(I)/Cu(II). The type of complex has been described somewhere on this forum. It's dark brown.

kronos - 23-2-2015 at 09:18

No i found that the darkness of that solution was due some dark particles... Now what the heck is that.. And yes i collected some of that foam and added HCl and it bubbled vigorously and disappeared.. What is going on here ??? :(

blogfast25 - 23-2-2015 at 09:48

Quote: Originally posted by kronos  
No i found that the darkness of that solution was due some dark particles... Now what the heck is that.. And yes i collected some of that foam and added HCl and it bubbled vigorously and disappeared.. What is going on here ??? :(


The bubbling is almost certainly due to peroxide + HCl.

The black specks might be CuO. If pH dropped a lot then Cu(OH)2 might have formed. With some heat that dehydrates very quickly to black CuO. Any heat used?

[Edited on 23-2-2015 by blogfast25]

kronos - 23-2-2015 at 11:04

Nope no heat used at all.. Rather the vineger was a little cool.. It came out from the fridge.. And i used after the temperature came nepar room temperature