[ldanielrosa]

I know that CuCl isn't highly soluble in water, but is there a way to reduce it further?  I have some used ferric chloride etchant that I would like to re-employ for something else, but the copper would complicate things.

Changing the pH with NaOH to facilitate complete precipitation should not be a problem as I can bring it back with HCl, and NaCl in solution probably won't be a problem as the target will be insoluble in water.

I should mention htat it's been fifteen years since I took a class, and it was 101.

[Borek]

Are you sure it is CuCl, not CuCl₂?

In the latter case adding some iron filings and filtrating them later (or decanting solution) should help.

NaOH will preciptate Fe as well.

[AWK]

Just add water.  CuCl has a solubility of 10^-3 mole/liter but you have additional Cl^- anions from FeCl2, hence solubility of CuCl will be much lower.

[ldanielrosa]

Thanks for the quick replies.  My merck index does not cover the specific solubility of all entries.  Nor does it contain an activity series.

That much having been said, I figured it would be best to convert all of the remaining FeCl3 either to FeCl2 or CuCl.  It wasn't very aggressive with copper pieces, but ate the steel wool like candy. Now it's muddy with scum crystalizing on the surface.  That which has passed through a filter has a bluish-greenish precipitate that has formed (so I assume) on cooling.  I hope the green liquid (relatively transparent) is moderately clean FeCl2.  I'll be back later, and I'll yet you know if I set my hair on fire.

[woelen]

Have a look at the colors of solutions of ferrous salts. A solution of ferrous chloride is almost colorless or very pale green. Both Fe(2+) ion and Fe(3+) ion is almost colorless. The colors, observed in iron-containoing solutions, usually is due to contamination, or due to hydrolysis or complex formation.

http://woelen.scheikunde.net/science/chem/solutions/fe.html

Copper (I) chloride is almost insoluble in water, but it is quite soluble in solutions, containing chloride. The common ion effect does not hold here, because CuCl forms a complex with chloride. The complex ion CuCl2(-) is formed, which gives soluble species in solution.

if you really want to get rid of all copper in the solution, then add a large excess amount of iron, such that finally, some iron (and copper metal as well) remain undissolved. The liquid should become pale green. Plain iron wool or steel wool is not really suitable. That contains quite some impurities, such as nickel, chromium, and even carbon. The chromium makes the liquid appear deep green, and the nickel also adds green ions to solution. The color of chromium ions and nickel ions is MUCH stronger than the color of iron (II) ions. So, I'm afraid that your solution is very impure and has a lot of other metal ions in solution.

Copper (II) ions also form a green ion in the presence of chloride, then you get the green CuCl4(2-) complex. As you see, things are much more complicated than you initially thought.