Sciencemadness Discussion Board

Preparation of sulfur

plasma - 20-5-2002 at 19:11

I belive sulfur can be made this way :

CaSO4 + 2C -> CaS + 2CO2 (heated)
CaS + 2HCl -> CaCl2 + H2S (H2S is very toxic gas)
Three ways of oxidizing hydrogensulfide :
2H2S + O2 -> 2H2O + 2S (Use charcoal dust as catalyst)
2H2S + SO2 -> 2H2O + 3S
2H2S + O2 -> 2H2O + 2S (H2S is burned in air)

I know theese reactions accur, but I don't know at which tempratures. Any comments ?
(I know sulfur can easely be obtained in stores, but unfortunantly that's not a fact in Norway)

madscientist - 20-5-2002 at 19:12

You could react the CaS with H2O2, much simpler.

8CaS + 8H2O2 --> 8Ca(OH)2 + S8

plasma - 20-5-2002 at 19:12

Thanks ! never thought of that one.
Will this reaction work with 5% H2O2.

plasma - 20-5-2002 at 19:13

CaS is a shiny transparent mineral, right ?

BTW why did you write :
8CaS + 8H2O2 -> 8Ca(OH)2 + 8S
and not just :
CaS + H2O2 -> Ca(OH)2 + S

What temperatures should be used +

Thanks

plasma - 20-5-2002 at 19:15

Correction :
CaS is not a shiny transparent mineral, it's a grey solid. CaS is also fluorescent, this means it glows in the dark.

NOTE: The temperatures needed for the reaction is rather high and it should be done in a cheramic bowl. I heated this mixture (CaSO4 & C) in a steel vessel, after 25 minutes of heating the vessel started to melt.

PHILOU Zrealone - 10-4-2003 at 12:42

The fact CaS is fluorescent lyes in the fact the impure CdS and ZnS are in too when natural mineral is analysed! Synthetic CaS displays no fluorescence!
:)

Blind Angel - 10-4-2003 at 12:48

he didn't wrote:
8CaS + 8H2O2 -> 8Ca(OH)2 + 8S
he wrote (sub added):
8CaS + 8H<sub>2</sub>O<sub>2</sub> -> 8Ca(OH)<sub>2</sub> + S<sub>8</sub>

S<sub>8</sub> is OctoSulfur, i know it exist but i dont know much else sorry

Theoretic - 30-6-2003 at 06:53

H2S could be decomposed by heat at about 400C.
I don't know how you could make use of H2, though.

blip - 30-6-2003 at 07:44

Quote:

You could react the CaS with H<sub>2</sub>O<sub>2</sub>, much simpler.

8CaS + 8H<sub>2</sub>O<sub>2</sub> --> 8Ca(OH)<sub>2</sub> + S<sub>8</sub>


Are you sure this wouldn't produce CaSO<sub>4</sub> instead? I've seen H<sub>2</sub>O<sub>2</sub> used to convert PbS to PbSO<sub>4</sub> to restore old paintings.

vulture - 30-6-2003 at 08:45

True, I was thinking of the same problem.
The H2O2 method will work with H2S IIRC.