Sciencemadness Discussion Board

Elemental sulfur and fecl2 to fecl3

Random - 26-8-2010 at 14:54

32 FeCl2 + 8 SO2 + 32 HCl → 32 FeCl3 + S8 + 16 H2O

I found this reaction here:

http://answers.yahoo.com/question/index?qid=20080410180336AA...

It looks like a good way to make elemental sulfur and FeCl3 at the same time, but is this possible?

aonomus - 26-8-2010 at 15:05

I must wonder, (not being rude at all, just curious), why make elemental sulfur (easy to get) from the harder to acquire, store, and handle FeCl2, and SO2? I suppose it would be a good way of scrubbing SO2 out of the air *if* it worked, but that is alot of FeCl2 for just a little bit of sulfur.

Jor - 26-8-2010 at 17:09

If it works, the availability of the FeCl2 is no problem. Just dissolve iron in excess hydrochloric acid, and use this solution for absorbing SO2. However, you are only gonna get 32g sulfur max for every 220g of iron. And generating the sulfur dioxide in quantities to obtain a usable amount of sulfur is a troublesome, as it is quite toxic. Besides, I'm pretty sure absorption of the gaseous SO2 in the Fe(II) solution is far from 100% efficient.

But yes if you really can't get sulfur, this might be a way to go. You need lots of iron, HCl and sulfite (K-metabisulfite is very cheap at wine-making suppliers). FeCl2 can be regenerated from FeCl3 by just adding iron to the solution.

But if you really can't get sulfur and are not worried about generating SO2, why not just acidify a solution of sodium thiosulfate with HCl? This produces S8 and SO2. Thiosulfate is very easy to acquire AFAIK.

Random - 26-8-2010 at 23:31

Well, this could be interesting experiment, though I am a little bit scared of SO2. I have K-metabisulfite so I don't have a problem in obtaining chemicals.

Could a similar method be used to obtain phosphorus from it's oxides?

[Edited on 27-8-2010 by Random]

not_important - 27-8-2010 at 13:52

Not that the reverse reaction can happen:

2FeCl3 + SO2 + 2H2O => 2FeCl2 + H2SO4 + 2HCl

promoted by mild alkaline conditions.

As for phosphorus from its oxides - no.