Uploaded April 2017 | Updated September 2026, 1 week ago
You can skip the preparation at 0:32
In this video, we continue our chalcogens in KCN series by dissolving some elemental Sulphur in boiling KCN solution. At first it appears as if not much is happening. When we acidify it with HCl no Sulphur is formed (in comparison to Se and Te). To show that KSCN has formed a few drops are added to an FeCl3 solution which immediately turns dark red. Above you can see some brown stuff which is from the reaction between FeCl3 and the Cyanide and after a while the top layer had turned blue from the formation of prussian blue.
You can skip the preparation at 0:32
In this video, we continue our chalcogens in KCN series by dissolving some elemental Sulphur in boiling KCN solution. At first it appears as if not much is happening. When we acidify it with HCl no Sulphur is formed (in comparison to Se and Te). To show that KSCN has formed a few drops are added to an FeCl3 solution which immediately turns dark red. Above you can see some brown stuff which is from the reaction between FeCl3 and the Cyanide and after a while the top layer had turned blue from the formation of prussian blue.
 (???) [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.")
