Making Copper Chloride: 2nd Oxidation State & Hydroscopicity

[Squall]

For the past few weeks i have been trying to make copper chloride. I was successful in making it two different ways, but it turns out that the copper chloride that i get is in its 2nd oxidation state.
And I am wondering if it was in it's first oxidation state would it not be so hydroscopic. Because copper chloride2 is very hydroscopic just leaving it out in air for a few minutes makes it moist.
And if its not as hydroscopic is there a way to make copper chloride1.

 

[mrjeffy321]

Because copper chloride2 is very hydroscopic just leaving it out in air for a few minutes makes it moist.

Really, Moist?
The Copper (II) Chloride I made will dry out in the air and form green crystals. After a while (days, if not weeks), parts of the CuCl2 will slowly turn blue as it becomes Hydrated, but it never gets moist.

Cu+1 salts are a little dificult to make since they are easily oxidized in the air and Cu+2 is so much stabler.
But the first step in the process I would say would be to make a solution of Cu+1 ions. This can be done by reducing some Cu+2 ions with Copper metal powder,
Cu+2 (aq) + Cu (s) --> 2Cu+1 (aq)
You can tell this has occurred since the color of the solution will change from the characteristic blue of Cu+2 in aqueousl solution to a slight yellowish-tan color of the Cu+1 ions.
The problem with this is that most common Cu+1 salts are not all that soluble...CuCl only has a solubility of about .63 g/ 100 mL, whereas CuCl2 is very soluble soluble.
Afterward, it would merely be a matter of precipitating them out without changing their oxidation state in the process. Adding some NaCl to the Cu+ soluble should precipitate out the CuCl.

CuCl MSDS:
http://www.jtbaker.com/msds/englishhtml/C5949.htm

 

[Squall]

I am not sure then what is going on then. Mabey i have something else. I put a litle into a dessicator about two days ago and when i took it out today and crushed it up. mabey it wasnt dried all the way. I Hope that's it. I have some pictures, but i don't know where to upload them to. But thanks for making things clear. If i undestand u right CuCl+2 shouldn't be very hydroscopic.

 

[mrjeffy321]

From my personal experience, CuCl2 is hygroscopic, yes, but not to the extent to which you are describing almost like NaOH or CaCl2.
All I have seen my CuCl2 crystals do is turn from green to blue (now why they lost the water in the first place and then later re-absolrbed it, I don't know).

I have pictures of some CuCl2 crystals of mine. I made the CuCl2 by reacting CuO with HCl, which left me with a very concentrated, dark green, CuCl2 solution which was probably pretty acidic too. I left it out (forgot about it) for about a month, a when I came back, all these needle-like clusters of crystals has formed on the sides and bottom of the container.
It certainly did not take the whole month to dry, I made another batch and left it in a container which allowed a larger exposed surface area to evaportate and it only took a coulple of days in the sun.
http://i62.photobucket.com/albums/h104/mrjeffy321/PH-CuCl2/CuCl2_Crystals1.jpg"
http://i62.photobucket.com/albums/h104/mrjeffy321/PH-CuCl2/CuCl2_Crystals2.jpg"
You can either attach your pictures to the post and wait for them to get approved, or you can just link to them from a image hosting site like what I do.

 

[Squall]

Yeah i am pretty sure that my crystals were not dry yet. sorry about that. Nice pictures.

 

[Cesium]

Pure copper (I) chloride is a white compound. Preparations are always light green because of oxidation from the air to copper (II). The copper (I) ion is relatively unstable both in and out of solution. In solution, it tends to dispropionate into copper and copper (II). (Copper (I) chloride is fairly stable in solution because it is insoluble in water.) Any homemade sample of copper (I) chloride will be contaminated with fairly large amounts of copper (II) oxychloride and copper (II) chloride due to aerial oxidation.

 

[mrjeffy321]

In the http://en.wikipedia.org/wiki/Copper(II)_chloride#Chemical_Properties" on CuCl2, they state,

Reduction to copper(I) chloride can be effected simply by heating CuCl2 at high temperatures (about 1000 °C):

2 CuCl2(s) → 2 CuCl(s) + Cl2(g)​

However, it is generally more convenient to work in aqueous solution, and to use a reducing agent such as sulfur dioxide to make CuCl:

2 CuCl2(aq) + SO2 → 2 CuCl(s) + 2 HCl(aq) + H2SO4(aq)​

So it seems that if you have the ability to heat the CuCl2 you have produced in a controlled atmosphere (no Oxygen) to very high temperatures (1000 °C), Copper (II) Chloride will be reduced to Copper (I) Chloride, giving off Chlorine gas. But this is not very practical for home experimenters.
Bubbling SO2 gas through a solution of CuCl2 seems to be a much easier solution, precipitating out CuCl.
SO2 gas can be made by burning Sulfur with Oxygen (or using an oxidizer such as KNO3). Simply capture these gasses and force them to bubble through your solution.
One would then need to filter out the CuCl precipitate and dry it quickly enough before it gets oxidized.

 

[Cesium]

This may be easier:

Copper is oxidized by a mix of concentrated hydrochloric acid and
hydrogen peroxide. When the peroxide is used up and there is still an
excess amount of hydrochloric acid, then the copper (II) appears to
oxidize the copper metal, under the formation of an intensely colored
complex. (What is the constitution of this complex??)
When the solution is diluted with water, then the intensely colored
complex is destroyed and a white crystalline precipitate of CuCl is
formed. If too much water is used, then no clear precipitate is formed.

I've been able to make large amounts of CuCl in this way, but I've had no use for this compound. I believe it is used in some organic reactions as a catalyst because it's a fairly strong lewis acid.

 

[Artaxis]

Cesium is right, it's an easy way to make CuCl

The amount generated can be controlled by the concentration of H2O2 that you use

In my experience, 6% makes almost none, 30% (100 vol peroxide) will result in roughly a 20% volume of precipitate compared to volume of solution.

To purify, let the mix settle then pour off the solution. Fill with water & repeat until water looks clear. You'll have quite pure CuCl left after evaporating.