Sciencemadness Discussion Board

Possible complex of copper ions and carbonate?

Redshiftrider - 2-1-2019 at 13:13

Today I've done a bit of experimenting with electrolysis.
I made a sodium bicarbonate solution and electrolysed it with a titanium cathode, a copper anode and a 9v battery. Initially some copper(II)oxide and copper(I)oxide formed as expected but the solution turned blue which indicated the that there were copper ions in solution.

How exactly could this happen? Normally copper carbonate is insoluble in water and if that does not form anything copper hydroxide would form so the copper must somehow be encapsulated by something.

I've read some topic somewhere on the forums where some sort of complex of copper ions with carbonate ions might be formed, could it be that?

[Edited on 2-1-2019 by Redshiftrider]

Redshiftrider - 2-1-2019 at 14:14

After doing some more searching I found out that a pure form of azurite can be formed this way. While azurite is insoluble in water it can be formed during electrolysis this way. If I were to let the solution sit in an open container over a long time it would slowly form azurite crystals