Sulphides soluble in water
Answers
Soluble sulfides are definitely the alkali metal ones like K2S or Na2S In fact they are pretty hydroscopic and they tend to stink. Keep them basic please, otherwise you get H2S Solutions will dissolve more sulfur or even selenium because you form polysulfides. I once cleaned a selenium spill that way. Yikes what a mess…
Many transition metal sulfides are like rocks and don’t dissolve. In fact quite a few of them are minerals like ZnS (sphalerite, wurtzite) or Cus (covellite). Some of them may decompose in strong acids with the same stinky results. I hate rotting eggs, sorry.
But some of them may well be pretty resistant too like the plate structures ones such as MoS2 or PtS2 I used those as electrodes. The same thing goes for CuInSe2 (with chalcopyrite structure) that has been used as a semiconductor electrode in photoelectochemical cells with sulfide/polysulfide electrolytes. Stable under illumination for years.
The pyrites like FeS2 are disulfides (with S2−2 dianions) Pyrite itself is very insoluble; micromolar [Fe2+] will react with picomolar [ HS−2 ] to precipitate it. Equilibrium constants are known for such things. It is why it is a very common mineral that forms is all sorts of environments. Acids might solubilize it a bit especially if you start forming the infamous stinky stuff. (But why would anybody in his right mind want to do that?) To dissolve it, it is mostly roasted to give the oxides. It can oxidize slowly to form sulfate though. There’s a whole family of pyrites with various d-metals, I think similar properties apply.
So, it’s a mixed bag.
Answer:
Explanation:
Soluble sulfides are definitely the alkali metal ones like K2S or Na2S In fact they are pretty hydroscopic and they tend to stink. Keep them basic please, otherwise you get H2S Solutions will dissolve more sulfur or even selenium because you form polysulfides. I once cleaned a selenium spill that way.
Many transition metal sulfides are like rocks and don’t dissolve. In fact quite a few of them are minerals like ZnS (sphalerite, wurtzite) or Cus (covellite). Some of them may decompose in strong acids with the same stinky results. I hate rotting eggs, sorry.
But some of them may well be pretty resistant too like the plate structures ones such as MoS2 or PtS2 I used those as electrodes. The same thing goes for CuInSe2 (with chalcopyrite structure) that has been used as a semiconductor electrode in photoelectochemical cells with sulfide/polysulfide electrolytes. Stable under illumination for years.
The pyrites like FeS2 are disulfides (with S2−2 dianions) Pyrite itself is very insoluble; micromolar [Fe2+] will react with picomolar [ HS−2 ] to precipitate it. Equilibrium constants are known for such things. It is why it is a very common mineral that forms is all sorts of environments. Acids might solubilize it a bit especially if you start forming the infamous stinky stuff. (But why would anybody in his right mind want to do that?) To dissolve it, it is mostly roasted to give the oxides. It can oxidize slowly to form sulfate though. There’s a whole family of pyrites with various d-metals, I think similar properties apply.
So, it’s a mixed bag.