Sulfur from a sulfate..?

[FadeToBlackened]

IM curious, would it be possible to extract sulfur from a sulfate similar to WP from a phosphate (pyrolysis with carbon and SiO2)? I know sulfur can be bought, but I like knowing stuff (who doesnt?)

[Lagen]

Reduce calcium sulfate with carbon at red heat, treat the resulting calcium sulfide with hydrochloric acid and bubble oxygen through the solution to oxidize the H2S:

CaSO4 + 4 C ---> CaS + 4 CO
CaS + 2 HCl ---> CaCl2 + H2S
2 H2S + O2 ---> 2 H2O + 2 S

But this should not be attempted as H2S is extremely poisonous. CaS itself is oxidized very easily and both Ca and S are consumed. It can be reduced to S with SO2. A much better way is to start from sodium thiosulfate (photographic hypo) and treat it with hydrochloric acid, or warm glacial acetic acid:

Na2S2O3 + 2 HCl ---> S + SO2 + 2 NaCl + H2O
Na2S2O3 + 2 CH3COOH ---> S + SO2 + 2 CH3COONa + H2O

Another way of making S is by thermal decomposition of pyrite, FeS2 above 600°C. (I can get pyrite from coal near where I live.)

[Arkangel]

Hate to sound flippant, but why not just buy it?

[Lagen]

[quote]I know sulfur can be bought, but I like knowing stuff (who doesnt?)<hr></blockquote>
Here where I live I buy it for 70c/kilo, pharmaceutical grade costs $6.30/kilo.

[Pu239 Stuchtiger]

[quote]But this should not be attempted as H2S is extremely poisonous.<hr></blockquote>

It is the gas that they add to natural gas so that you will smell a gas leak, is the gas responsible for the rotten egg smell, and is what makes skunk spray wreak. Your nose can smell it in concentrations as low as 0.02ppm. The smell becomes intolerable long before it becomes dangerously poisonous. However, after a while it begins to have an anesthetic effect on the nose (thats why farmers "get used" to the smell of shit, which also smells terrible because of H2S).

It shouldn't be too much of a worry as long as you conduct these experiments outside. If you no longer smell the hydrogen sulfide, then leave, because its anesthetic property is taking effect. If hydrogen sulfide in low concentrations could kill, then accidental death-by-fart would be a widespread problem. :D

However, if it is possible to use the other methods Lagen suggested, avoid the one involving the hydrogen sulfide.

[nbk2000]

Utilities use ethyl mercaptain, not H2S. Lower detection threshold, less toxicity.

[Pu239 Stuchtiger]

Hmm I read that in a 20 year old book so they must have changed it...oops.

[FadeToBlackened]

Would the H2S not fly off with the addition of acid?

[Lagen]

H2S has a fairly low solubility, about 0.002, so you would use a lot of water and add the HCl slowly, to avoid the H2S being expelled because of common ion effects. Or just collect it under a siphon or something, easier and safer. Regarding the toxicity, breathing 1000 ppm for a few moments is lethal, IIRC. The concentrations you encounter in farts are much lower. I read some pretty scary stories about factory accidents on the newsgroups. I once had an accident with it (preparing sodium sulfides on the hotplate when the beaker cracked), the concentration went beyond the "no smell" level, nothing happened to me except I was stoned like hell for a few hours. Won't do it again.

[fasa]

Is it possible to extract sulfur from ammonium sulfate?

[jeffchem2000]

according to a book I have H2S can be converted to H2 and S by passing H2S over an electric arc or spark. Although it must be quite dangerous because any air near to the spark would react with the sulphur and also the hydrogen causing it to burn or explode.