Sciencemadness Discussion Board

insoluble copper chloride?

vampirexevipex - 8-4-2012 at 16:10

I was using copper chloride and accidentaly mixed H2O2 with it. It turned dark brown and after awhile it turned into a insoluble pale green precipitate. Can someone explain me WTF happened? And how do i make it turn back to normal?

barley81 - 8-4-2012 at 16:43

Copper (I) chloride, anhydrous copper (II) chloride, or copper (II) chloride dihydrate?

weiming1998 - 8-4-2012 at 21:12

2CuCl2(aq)<===>2Cu(2+)+4Cl-
H2O2(aq)+2Cl-<===>2HOCl(aq)+2e-
Cu(2+)+e-===>Cu+
Cu(+)+Cl-===>CuCl(s)

The green colour is some of it partially converting back into CuCl2.

That's what I think. I can't find any references

[Edited on 9-4-2012 by weiming1998]

vampirexevipex - 9-4-2012 at 02:55

Quote: Originally posted by weiming1998  
2CuCl2(aq)<===>2Cu(2+)+4Cl-
H2O2(aq)+2Cl-<===>2HOCl(aq)+2e-
Cu(2+)+e-===>Cu+
Cu(+)+Cl-===>CuCl(s)

The green colour is some of it partially converting back into CuCl2.

That's what I think. I can't find any references

[Edited on 9-4-2012 by weiming1998]


But doesnt have to be water soluble? I left it undisturbed for a few days and its still insoluble, oh i forgot to say that it was copper ll chloride dihydrate

weiming1998 - 9-4-2012 at 03:09

CuCl, or Copper (I) chloride, is insoluble. I suspect that your solution is concentrated enough so that the oxidized CuCl, which is CuCl2, isn't dissolved back into the solution.

LanthanumK - 9-4-2012 at 05:54

Was your copper(II) chloride from a chemical supply shop? It shouldn't do this; it should just catalytically decompose the H2O2.

If you made it from copper metal, you likely have some copper(I) chloride dissolved into it. The hydrogen peroxide oxidizes this copper(I) chloride to an insoluble basic copper(II) chloride.

Chloride and peroxide are not such strong reducing agents that they can reduce copper(II) to copper(I), weiming1998.

Reactions: CuCl2 + Cu --> 2 CuCl

2 CuCl + H2O2 --> 2 Cu(OH)Cl (ultimately)

weiming1998 - 9-4-2012 at 06:39

Quote: Originally posted by LanthanumK  
Was your copper(II) chloride from a chemical supply shop? It shouldn't do this; it should just catalytically decompose the H2O2.

If you made it from copper metal, you likely have some copper(I) chloride dissolved into it. The hydrogen peroxide oxidizes this copper(I) chloride to an insoluble basic copper(II) chloride.

Chloride and peroxide are not such strong reducing agents that they can reduce copper(II) to copper(I), weiming1998.

Reactions: CuCl2 + Cu --> 2 CuCl

2 CuCl + H2O2 --> 2 Cu(OH)Cl (ultimately)


Oh, ok. But, I found this http://www.ncbi.nlm.nih.gov/pubmed/3009503
It states on the website that a mix of Cu2+ ions, H2O2 and NaCl can generate HOCl. What would cause this?


LanthanumK - 9-4-2012 at 09:05

H2O2 + NaCl + Cu++ + 2 H2O --> HClO + H2O + Cu(OH)2 + Na+ + H+ is a possibility. NaClO will oxidize Cu(I) to Cu(II), being reduced to Cl(-).

woelen - 9-4-2012 at 09:57

Add a drop of hydrochloric acid to dissolve the precipitate. Then you should boil for a while to get rid of all H2O2.

AJKOER - 9-4-2012 at 13:09

First, a limited hydrolysis of CuCl2 in water:

CuCl2 + 2 H2O <----> Cu(OH)2 + 2 HCl

But, with the addition of Hydrogen peroxide:

H2O2 + 2 HCl (dilute only) --> 2 HOCl

This reaction is cited by Watt's as one of several preparations for Hypochlorous acid. To quote from "Watts' Dictionary of chemistry", page 16. "—6. Addition of H2O2 Aq (containing 2.45 p.c. H2O2) to a large excess of Cl Aq produces HClOAq, according to Fairley (B. A. 1874, 57); if much H202 is added, the HClO Aq is decomposed forming HCl Aq, H20, and evolving O." Link: http://books.google.com/books?pg=PA13&dq=Watt+preparatio...

Next, the reaction of dilute HOCl and Cu(OH)2, forming Copper Oxygen Chloride, a greenish crystalline double salt, CuCl2.Cu(OH)2, which is insoluble in water.

2 Cu(OH)2 + 4 HOCl --> 2 CuCl2.Cu(OH)2 + 2 H2O + O2

You should also see some oxygen bubbles. The reaction is actual more complex with the intermediate formation of Copper hypochlorite, which decomposes forming the oxychloride and, per the reference below, actually leaves some CuCl2 in solution.

Reference: "A comprehensive treatise on inorganic and theoretical chemistry", Volume 2, by Joseph William Mellor, page 271. To quote:

"R. Chenevix notes the ready solubility of cupric oxide in chlorine water, and P. Grouvelle found that the soln. obtained by passing chlorine into water with cupric oxide in suspension possessed bleaching properties, and these were retained even after the soln. had been boiled for a quarter of an hour. A. J. Balard found that the distillation of P. Grouvelle's liquor furnished some hypochlorous acid and a green oxychloride, 3CuO.CuCl2.4H20, was formed in the retort. A. J. Balard prepared a soln. of cupric hypochlorite by dissolving cupric hydroxide in hypochlorous acid. It is also made by the action of cupric sulphate on calcium hypochlorite. A. J. Balard found that copper filings are partially dissolved by hypochlorous acid, the soln. after standing some time contains cupric chloride, and deposits a green pulverulent cupric oxychloride."

Link:
http://books.google.com/books?pg=PA269&lpg=PA274&dq=...


[Edited on 9-4-2012 by AJKOER]

symboom - 3-10-2016 at 01:10

Same here I never heard of copper oxychloride left a solution of hcl and hydrogen peroxide in us nickel and I ended up with this white light green powder on the nickels like you have also I think I makes chlorine gas if you mix with sodium hypochlorite??? Also a color change is observed
Doesnt make sience to me but it smells like it. No bubbles though? And a black ring where the solution was on the wall of the container

[Edited on 3-10-2016 by symboom]

[Edited on 3-10-2016 by symboom]

unionised - 3-10-2016 at 03:20

Quote: Originally posted by vampirexevipex  
I was using copper chloride ...

What were you using it for?
For example, were you using it to etch copper?