Uploaded November 2017 | Updated September 2026, 1 week ago
If you have seen our video on the equilibrium between [Co(H2O)6](2+) and [CoCl4](2-) you probably thought this could be possible with similar compounds as well.
So what we did here was to mix CuCl2 with H2O and HCl to a ratio where the nearly colorless, blue [Cu(H2O)6](2+) is turned into the green [CuCl4](2-) when it is heated.
If you have seen our video on the equilibrium between [Co(H2O)6](2+) and [CoCl4](2-) you probably thought this could be possible with similar compounds as well.
So what we did here was to mix CuCl2 with H2O and HCl to a ratio where the nearly colorless, blue [Cu(H2O)6](2+) is turned into the green [CuCl4](2-) when it is heated.
 (???) [no audio]](https://i.ytimg.com/vi/p8TuAZuQeTU/mqdefault.jpg "Cobalt Chemistry: [Co(CO3)3](3-) (???) [no audio]
If Co(II) solutions are treated with alkaline H2O2 Co2O3 and CoO2 may form. If however the precipitate from Sodium Bicarbonate and Cobalt Chloride is oxidized with a 10 M H2O2 at cold temperatures a green product froms.
Well we used worm solutions, 3% Hydrogen Peroxide and Sodium Carbonate but still got a green compound. Of course we cant be sure about its composition that way. It could also be the different oxides but the green color at least indicates some of the complex might have actually formed that way.
The Co(II) is oxidized to Co(III) which forms an insoluble complex with Na2CO3, Na3[Co(CO3)3]. Interesting enough the carbonate can be easily substituted for other ligands making this complex a great precursor to other Co(III) compounds.
We already discussed the chemistry of Co(II) and Co(III) in another video and showed that the oxidation potential is highly dependend on the system you use Cobalt in.")
