Sciencemadness Discussion Board

Removing HCl from CuCl2 solution

Draeger - 11-6-2020 at 12:19

So, I made some copper(II) chloride today. Problem is excess HCl and only things I can think of to neutralize it is sodium hydroxide and sodium bicarbonate, and I imagine that sodium bicarbonate would be the best choice, but I don't know.

[Edited on 12-6-2020 by Draeger]

Lion850 - 11-6-2020 at 12:46

Can you boil out the excess HCl?

Draeger - 11-6-2020 at 12:57

Quote: Originally posted by Lion850  
Can you boil out the excess HCl?

I forgot to mention: I have little to no ventilation, so that would be pretty risky.

unionised - 11-6-2020 at 13:08

Dry it in a desiccator over NaOH (or even NaHCO3, if that's all you have).

Bedlasky - 11-6-2020 at 13:13

If you have only slightly excess of HCl, just let it slowly evaporate. It should be fine.

[Edited on 11-6-2020 by Bedlasky]

Draeger - 11-6-2020 at 23:59

The solution no longer smells stinging, so maybe I could heat it up a little. I could maybe attach a ph test strip above the beaker so that I am warned if dangerous amounts of HCl are being evolved.

Tsjerk - 12-6-2020 at 01:47

I think the pH test strip will turn red soon, even with small amounts of HCl. I think you can trust your nose in this one, once you start to smell the HCl it is time to stop, by that time most likely nothing dangerous evaporated yet.

Be aware of HCl's astonishing power to corrode (stainless) steel though! It will leave a dull grey to dirty brown staining on anything made with iron in it, and will do so quickly.

Syn the Sizer - 12-6-2020 at 04:59

I agree with Tsjerk, I had pH paper sitting on the counter nest to my bottle of HCl which I stupidly left open for an hour or so and my whole book of pH paper turned acidic. Your nose is your best piece of equipment.

If you have the equipment you could use a ground joint flask with a gas takeoff and bubble the fumes through a NaOH bath, of course having a trap to catch any suck back.

I would avoid neutralizing with anything, I made some CuCl2 with some basic copper (II) carbonate that I didn't wash fully and the residual sodium salts left were a pain to remove. they would form clusters around the nice CuCl2 crystals as well the sodium salts also climb the side of the crystallization vessel, green of course showing a loss in yield of CuCl2.

Bedlasky - 12-6-2020 at 08:05

Quote: Originally posted by Syn the Sizer  

I would avoid neutralizing with anything, I made some CuCl2 with some basic copper (II) carbonate that I didn't wash fully and the residual sodium salts left were a pain to remove. they would form clusters around the nice CuCl2 crystals as well the sodium salts also climb the side of the crystallization vessel, green of course showing a loss in yield of CuCl2.


I once try if I can grow Na2[CuCl4] crystals from CuCl2+NaCl solution. This was failure, I had only mix of CuCl2 and NaCl. So I recrystallized CuCl2 from ethanol - this is good way how to remove NaCl contamination.

Syn the Sizer - 12-6-2020 at 11:57

I feel stupid, I knew CuCl2 was soluble in ethanol but NaCl was not. I will need to keep that in mind if I encounter this again.