[Athrax]

Hello,

As you all know, it gets harder and harder for us hobby chemists
to source chemicals. For an experiment I need an amount of roughly
100 grams of CuCl2 in HCl solution.

The catch? Where I live, I can source no copper compounds and no
oxidizers. No peroxide, no nitric acid, nothing. Best I have to
supply oxygen is an old fishtank airpump, and whatever chemicals
the local hardware store happens to carry.


So, what DO I have available:

Pure copper, in the form or stripped electrical cables.
Muriatic acid, 37%, industrial grade.
Sulfuric acid, 60%, industrial grade.
Sodiumbicarbonate (aka baking soda).
Sodiumchloride.
Time. Whether I have to wait an hour or a week for my CuCl2 does not matter.

So, how to get from that to CuCl2.


Idea 1>

Electrolysis of the copper in aqueous NaCl solution. The result is
CuCl2, but I'll still have some NaCL in the solution, as well as NaOH.
The NaOH could be neutralized with HCL, but then I still am stuck
with a mix of CuCl2 and NaCl, but I need to remove the NaCL from
this, and I'm not gonna crystalize it out and then sort crystals by
color, sorry.


Idea 2>

Electrolysis of the copper in H2SO4 solution. Apart from CuSO4 I likely
will get plenty of copper sponge on one of the electrodes.

Evaporate the water from the solution, then filtrate off any remaining H2SO4
if necessessary. The residue should be a mix of elementary copper sponge/dust
and CuSO4. Add water to dissolve the CuSO4, leaving the copper sponge/dust.

Add baking soda to the dissolved CuSO4, and I should get a precipitate of
CuCO3 which can be filtrated out and rinsed since it is barely water soluble.
Dissolve this in HCL to get the CuCl2 I want.

The copper dust/sponge from earlier I could heat/roast to form copper oxide,
which could be added to the HCL as well, adding to the CuCl2 concentration
in my solution.

I'm just not sure if I'm overlooking something here, or if there is an easier way
to obtain mostly pure CuCl2 with the limited means available to me, and I'd be
thankful for any kind of input I could get.

Thank you,
-Athrax

[Arkcon]

The second on seems like the best method to me.  Where I used to work, copper sulfate was made a different way -- from copper, sulfuric acid, and bubbled air.  So you can then precip, and redissolve in HCl.

Why do you need this particular reagent?

[Athrax]

Hello,

and thank you for the quick reply.

I do need the CuCl2 in HCl to etch printed circuit boards.
The ferric chloride I used to use unfortunately is not being
sold here anymore, most other alternatives do require the
addition of H2O2 (also not available) to speed up the etching
process, and of the remaining options the CuCl2 in HCl
solution still seems to be the best. It is stable and can be
stored for a long time, and instead of having to dispose it
off after usage you can regenerate it by bubbling air into
the solution.

So CuCl2 in HCl it is.

Best regards,
-Athrax

[Zyklonb]

I would bubble air in a HCl solution with copper, or try electrolysis in the same.
Or, electrolysis in a NaCl solution, then add NaOH or Na₂CO₃ to precipitate copper hydroxide or carbonate respectively, then add HCl (aq) and you've got a copper chloride solution.
As a last resort, depending on where you live I can sell you some anhydrous CuCl₂, but I don't have more than 30 grams at the moment.
[EDIT] Typo

[Athrax]

Hmmm..

Bubbling air into a 50% H2SO4 solution had no effect to the copper
for whatever reason, so I'm ruling out this method.

Electrolysis of the same 50% H2SO4 solution with copper electrodes
is slowly eating away the copper, as expected. But it's a lot slower
than expected.

An electrolysis of saturated NaCl solution with copper electrodes does
yield a lot of yellow-orange precipitate, which could be Copper-I-Oxide
or hydroxide. It's considerably faster than the electrolysis in H2SO4 anyway,
so I'm taking this route for now, then will precipitate out whatever CuCl2
is in the solution with Sodiumcarbonate, and filtrate. Both the resulting
CuCO3 and Cu2O/Cu(OH)2 should readily dissolve in HCl and yield the CuCl2 I'm
after.

Since I got time, I might as well see if either bubbling air in HCl will
directly dissolve copper, or if electrolysis in HCl will yield any useable
results, but that's something for tomorrow.

Best regards,
-Athrax

[Arkcon]

Sorry, but you will need concentrated sulfuric to dissolve copper with bubbled air.  Copper doesn't undergo the hydrogen reaction with acids.  I don't think concentrated HCl will react, even with air.  Why can't you use household hydrogen peroxide with HCl?  After its all dissolved, you can recrystallize, to remove impurities.

[Athrax]

I WOULD use household grade H2O2 and skip all the scheningans
with the electrolysis if I could GET household grade H2O2 here.
I happen to be in the unfortunate situation that I live in Iceland,
where access to chemicals is a bit overregulated. I've been
through probably two dozen stores both big and small, and
neither the cleaners aisle at the local hardware stores nor the
pool chemicals corner does sell H2O2. The price for 100ml 4%
solution at the drugstore is in the $15 range, which is overpriced
enough to disregard this option, and the local hair salons only
have it in thickened up form as some kind of cream.

Anyway, I'm persistent, I'll get my CuCl2 one way or another,
and if this little project takes a month to finish, then so be it. :>

The electrolysis in strongly saturated NaCl solution yielded
quite a bit of orange precipitate. Could be anhydrous CuCl2,
I will see whether it turns green later or not. Introducing
a sodiumcarbonate solution into the filtered, almost clear
electrolysis fluid did not result in any precipitate whatsoever
though.

I'll finish up the (much slower) electrolysis in H2SO4 now,
then try the same directly with HCl. At least comparing all
three approaches is proving interesting enough to keep me
entertained.

Best regards,
-Athrax

[Athrax]

Hello,

after getting help here in the forum a few days ago and then doing
a bit more research on my own, I finally managed to create the CuCL2
I needed, without requiring any H2O2.

Before considering this topic finished, I'd like to report my own observations
and experiences. Maybe they'll help someone else someday. I do not lay any
claim to the scientific correctness of the following text. Please bear with
me, I'm an amateur at best.

To remind everyone of the original problem: Normally CuCl2 can be created
by adding Cu to HCl, using some H2O2 to get the reaction going. Unfortunately
there was no way for me to source any H2O2, so that I decided to take a
somewhat indirect route in creating the CuCl2.

Chemicals available were Cu (stripped electrical wire), HCl, H2SO4, NaCl and
NaHCO3, and of course H2O.

In order to react the copper with the HCl, it has to be converted into a compound
which readily dissolves in HCl. To do so, an electrolysis of copper electrodes in
aqueous solution of different salts was performed, trying different solutions
to find the easiest/most efficient way (The Na2SO4-solution did prove fastest,
followed immediately by the NaCl solution).

As power source for the electrolysis an old computer powersupply was used. Those
units easily can provide currents in excess of 20A at voltages of 3.3V, 5V and 12V.

As electrolyte were chosen: NaCl (rock salt), H2SO4 (drain cleaner), NaHCO3 (baking
soda), Na2CO3 (created by heating of NaHCO3) as well as Na2SO4 (reaction of Na2CO3
with H2SO4).

Saturated / highly concentrated solutions of each of those compounds were created,
1 liter of each. A copper anode of around 100g of weight was placed at the bottom of
the solution, in a pyrex beaker. (Disclaimer: Okay, actually I used my coffee jug. ).
The cathode consisted of a copper wire bent into a ring, sitting in the same container
about an inch above the anode, so that any elementary copper forming on the cathode
would fall off and down onto the anode, where it would again be available for the
electrolysis.

Depending on which electrolyte was used, the following copper compounds were
formed: CuCl/CuCl2, CuSO4, Cu(OH)2, CuCO3. Most of the solutions would also form plenty
of CuO and Cu2O as the reaction advanced and the amount of copper in the solution increased.

Apart from those copper compounds and the salts initially introduced into the reaction,
the solutions also would contain some elementary Cu in powder form, as well as reaction
products such as NaOH. Plenty of H2 would be released, while much of the O2 would react
with the copper ions in solution, forming oxides.

After the copper anode had fully dissolved, the solution containing H2SO4 was neutralized
with Na2CO3 in solution, which was created by heating NaHCO3 and dissolving it in water.
Both the CuSO4 and the CuCl/CuCl2 were precipitated out by adding an excess of Na2CO3 in
solution, which would turn the CuSO4 and CuCl/CuCl2 into Cu(OH)2, a step which would
prove of advantage during refinement of the reaction products.

So, to recapitulate, after several hours of electrolysis and the precipitation with Na2CO3
I ended up with roughly two gallons of aqueous solutions containing Cu, CuO, Cu2O, CuCO3,
Cu(OH)2, as well as Na2SO4, Na2CO3, NaHCO3, NaOH and NaCl.

Time to seperate anything containing copper from all the sodium compounds. The 2 gallons
of solution were poured together, the water boiled off, and the mix of Cu-powder, oxides
and different salts of both copper and sodium was roasted at 250°C for several hours.

Almost all of our copper products were decomposed to CuO by the roasting, while the
sodium compounds remained largely unchanged. And here also is the reason for turning
the CuCl/CuCl2 and the CuSO4 into Cu(OH)2 earlier. CuCl and CuSO4 are still relatively
stable at 250°C, while the Cu(OH)2 would fully decompose to CuO. And while CuCl and
CuSO4 are quite well soluble in water, our CuO is NOT.

So we refine our wild mixture of sodium salts and CuO by washing out the sodium salts
and filtering off the CuO, then drying it.

We are left with almost 500 grams of black CuO, red Cu2O and some leftover copper powder.

All three are added to concentrated HCl, where the oxides will readily dissolve, forming
a solution of mostly CuCl, with some bits of copper still floating in the solution. More
HCl is added, then a fishtank airpump is set up to bubble air into the solution. This
should be done in a well ventilated place.

After some days the CuCl will have reacted with the excess HCl and oxygen from the
air bubbled into the solution.

4CuCl + 4HCl + O2 -> 4CuCl2 + 2H2O

The CuCl2 in turn will react with the copper impurities in our solution, turning them into
CuCl while being reduced to CuCl itself, ready to again react with oxygen and HCl. Eventually
our solution should contain almost exclusively CuCl2, HCl and of course H2O.

The solution can be used to etch printed circuit boards, which adds more copper. After use
simply regenerate by bubbling air into it, and occassionally add more HCl.


Best regards,
-Athrax