 (Pd in HCl/H2O2) @colorfulchemistry2569](https://i.ytimg.com/vi/wQA5K90Ijqg/hqdefault.jpg)
Uploaded May 2017 | Updated September 2026, 1 week ago
Palladium is an interesting element. Being a Platinum-group metal and standing between Nickel and Platinum one might expect it to be unreactive. Funnily this is not the case and some people even joke it could be more reactive than Nickel. Obviously, this might be a bit too much but the reactivity can be compared to the one of silver with one important difference: Palladium usually does not build up many passive layers. Meaning that it can dissolve in HCl for example.
In this video, however, we cheated a little and this is first to make it shorter and second to make it more visible. Usually, oxygen in HCl is enough to slowly dissolve Palladium but we used H2O2 instead of the oxygen here. Now you might say there is no big difference but there is. The redox reaction now changed to the one of an acidified Peroxide which has a huge redox potential being capable of even dissolving gold and platinum to some extent!
And PdCl2 forms Pd(IV) in H2O2 as well!
Note however that we also tried it with HCl and Oxygen and a lot of boiling and it turned yellow as well!
What forms here is the complex [PdCl4](2-). While Nickel(II) already shows some square planar geometry, especially when working with cyano-Ligands for Palladium almost all complexes are square planar.
Also the coordination number of 4 is really common in Palladium chemistry. So if you have to guess, a square planar geometry is always a good guess when dealing with Pd(II). Even the aqua-complex only has 4 Ligands.
Palladium is an interesting element. Being a Platinum-group metal and standing between Nickel and Platinum one might expect it to be unreactive. Funnily this is not the case and some people even joke it could be more reactive than Nickel. Obviously, this might be a bit too much but the reactivity can be compared to the one of silver with one important difference: Palladium usually does not build up many passive layers. Meaning that it can dissolve in HCl for example.
In this video, however, we cheated a little and this is first to make it shorter and second to make it more visible. Usually, oxygen in HCl is enough to slowly dissolve Palladium but we used H2O2 instead of the oxygen here. Now you might say there is no big difference but there is. The redox reaction now changed to the one of an acidified Peroxide which has a huge redox potential being capable of even dissolving gold and platinum to some extent!
And PdCl2 forms Pd(IV) in H2O2 as well!
Note however that we also tried it with HCl and Oxygen and a lot of boiling and it turned yellow as well!
What forms here is the complex [PdCl4](2-). While Nickel(II) already shows some square planar geometry, especially when working with cyano-Ligands for Palladium almost all complexes are square planar.
Also the coordination number of 4 is really common in Palladium chemistry. So if you have to guess, a square planar geometry is always a good guess when dealing with Pd(II). Even the aqua-complex only has 4 Ligands.
 (Pd in HCl/H2O2)](https://i.ytimg.com/vi/wQA5K90Ijqg/mqdefault.jpg "Palladium Chemistry: [Pd(Cl4](2-) (Pd in HCl/H2O2)
Palladium is an interesting element. Being a Platinum-group metal and standing between Nickel and Platinum one might expect it to be unreactive. Funnily this is not the case and some people even joke it could be more reactive than Nickel. Obviously, this might be a bit too much but the reactivity can be compared to the one of silver with one important difference: Palladium usually does not build up many passive layers. Meaning that it can dissolve in HCl for example.
In this video, however, we cheated a little and this is first to make it shorter and second to make it more visible. Usually, oxygen in HCl is enough to slowly dissolve Palladium but we used H2O2 instead of the oxygen here. Now you might say there is no big difference but there is. The redox reaction now changed to the one of an acidified Peroxide which has a huge redox potential being capable of even dissolving gold and platinum to some extent!
And PdCl2 forms Pd(IV) in H2O2 as well!
Note however that we also tried it with HCl and Oxygen and a lot of boiling and it turned yellow as well!
What forms here is the complex [PdCl4](2-). While Nickel(II) already shows some square planar geometry, especially when working with cyano-Ligands for Palladium almost all complexes are square planar.
Also the coordination number of 4 is really common in Palladium chemistry. So if you have to guess, a square planar geometry is always a good guess when dealing with Pd(II). Even the aqua-complex only has 4 Ligands.")
![Copper Chemistry: Cu(II)/As(III) chameleon [no sound, 2x speed]](https://i.ytimg.com/vi/xHic2pew9bI/mqdefault.jpg "Copper Chemistry: Cu(II)/As(III) chameleon [no sound, 2x speed]
In this video, we show another way to make a beautiful spectrum of colors using Copper chemistry. The reaction is the following: Arsenic(III) is oxidized to Arsenic(V), while Copper(II) is reduced to Copper(I), all happening at a high pH value. But of course, we cannot just add cations and so different precipitates form and dissolve in this process creating many different colors.
We start off with a CuSO4 solution, which is light blue. To this, we add some NaAsO2. We already showed you Copperarsenite in another video. The blue-green precipitate also leaves a greenish aqueous layer on top. When we add KOH the remaining CuSO4 forms the dark blue Cu(OH)2. You can see the surface of the KOH turn dark blue. There is also an equilibrium between Arsenite and
Hydroxide and so the overall color turns more blueish in this process. Now the actual reaction also requires some heat. The KOH dissolving in so little water already causes it to become quite hot. This is why you suddenly see red-brown spots appearing everywhere. When we finally heat it all the Cu(II) is reduced to Cu(I) forming Cu2O.
Much like with our silver video, this is another case where some redox-reactions are just much easier accessible when high pH values are used.
For Arsenic(III to V) the potentials are 0,56 and -0,71 for pH=0 and 14 and for Copper(II to I) the potentials are 0,159 and -0,08.
To reduce Copper(II) to Copper(I) the redox potential of the reducing agent, here Arsenic(III) needs to be lower, which is only fulfilled at higher pH values.")
![Sulfur Chemistry: [Fe(CN)5NOS] from Sodium Polysulfide](https://i.ytimg.com/vi/xm7IYOrwQfA/mqdefault.jpg "Sulfur Chemistry: [Fe(CN)5NOS] from Sodium Polysulfide
There is an interesting reagent called Sodium Nitroprusside. It is sometimes used to identify several ions and is capable of distinguishing between Sulfite and Sulfide for example as well as forming many colored complexes. As we showed in our Cadmium Sulfide video, Sodium Polysulfide, made from elemental Sulfur and Sodium Hydroxide seems to be an alternative for the rather unstable Sodium Sulfide. So we tried to make the famous Sulfide test using Nitroprusside and a selfmade Polysulfide solution.
Here is the result. Note, as we didnt have any other source of H2S or Sulfide we could not compare this to the real test. So we assume the compound formed should have the composition as given in the title.")
