I'm wondering if the reaction of $\ce{KCl + CuCl2}$ in solution (aq) will produce any products (have a net ionic equation/solid precipitate)?

Using the metal activity series, I see that potassium is the most reactive, so it should displace the copper and form KCl again, but wouldn't that mean there was no reaction taking place?

I've came up with this $\ce{KCl + CuCl2 -> KCl + CuCl2}$, but not sure if it is correct.

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    $\begingroup$ There will be $\ce{[CuCl_x]^{n-}}$ in solution where x=3,4,5 and n=1,2,3 depending on concentration. They are called chlorocuprate ions. $\endgroup$ – Nilay Ghosh May 24 '18 at 6:26

For a dilute solution of copper(II) chloride in dilute aqueous potassium chloride there will be no reaction.

There will not be a redox reaction even if the potassium chloride solution is more concentrated, the only reaction which will occur when the chloride solution is high is the complexation of chloride anions to copper cations to form chlorocomplexes such as [CuCl4]2-.

In the solution as there is no reducing agent it will be impossible for a redox reaction to occur.

There will be exchange of chlorides between the two compounds, this could be shown by a radioisotope experiment using chlorine-36. I am sure if one was to get chlorine-35 enriched potassium chloride and chlorine-37 enriched copper chloride it could also be done if we had a mass spectrometer suitable for the measurement. But the radioactive experiment would be more able to give a better result.

For the dilute solution as the copper(II) and potassium chlorides fully dissociate and become seporated (fully solvated) ion pairs the chlorides will be interchanged between the two metals. If we were to start the experiment with copper(II) chloride and radioactive potassium chloride (how about a Cl-36 radiotracer in it). Then if we were to combine the two in water, then to evapourate the mixtrue down to a mixture of solid copper(II) chloride and potassium chloride. Then if we were to heat the mixture and evapourate off Cu2Cl4 vapour (this is the most likely gas state form of copper(II) chloride) then the radioisotope would be distributed between the copper and potassium chlorides.

If we were to start with a chloride complex of a metal which very slowly exchanges chloride (and other ligands) with what is in solution such as RhCl3(H2O)3 and the radioactive chloride in the form of KCl. Then if I was to dissolve the two together and then to seprate again the two chlorides then I would expect the majority of the chloride radioactivity to remain in the potassium chloride.


I agree with the theoretical renditions of my colleagues.

I also suspect that there may have been a reaction performed by Glace using his prepared cupric chloride (which likely had a high chloride concentration and was in contact with copper metal at some point), which eventually strangely appeared to produce a precipitate.

I explain my presumed formation of what I surmise is copper oxychloride as a result of a comproportionation reaction from the action of copper metal acting on cupric chloride (see https://en.wikipedia.org/wiki/Copper(I)_chloride ) in the presence of a high chloride concentration creating a soluble CuCl2- complex:

Cu(ll)L + Cu <--> 2 Cu(l)L (L here refers to a chloride ligand)

So Glace’s starting solution could have been a mix of complexed cuprous plus cupric chloride.

Of note is that there also exists an equilibrium reaction between water and the aqua cupric complex providing an acid source:

[Cu(H2O)6]2+ (aq) + H2O (l) = [Cu(H2O)5(OH)]+ (aq) + H3O+ (aq)

The final piece of the puzzle is the electrochemical reaction consuming the created H+ (moving the above equilibrium to the right) activated by the oxygen in air in the presence of cuprous:

4 Cu+ + O2 (from air) + 2 H+ → 4 Cu2+ + 2 OH- (source: Wikipedia reference above and also Eq (7) below)

A related reaction also occurs with ferrous, oxygen and a souce of H+ (see https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/html/final-78.html ).

Here is an extract from Wikipedia (see https://en.wikipedia.org/wiki/Dicopper_chloride_trihydroxide ) on the reactions associated with the preparation of copper oxychloride:

“ CuCl2 + Cu + 2 NaCl → 2 NaCuCl2 (eq.6)

6 NaCuCl2 + 3/2 O2 + H2O → 2 Cu2(OH)3Cl + 2 CuCl2 + 6 NaCl (eq.7) “

where Eq (6) produces a soluble cuprous complex which feeds Eq (7), an electrochemical reaction.

Copper chemistry can be a bit surprising at times.


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