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|OTP appearance||colorless gas|
|Immediate Danger to Life and Health||100ppm|
Hydrogen sulfide is a toxic gas evolved from and involved with a variety of processes. Heavier than air.
- used to precipitate certain metal ions (Pb,Cu,Hg,As) in solution:
- Source of sulfur via the Clause Process:
- 2 H2S + 3 O2 → 2 SO2 + 2 H2O
- 4 H2S + 2 SO2 → 3 S2 + 4 H2O
- as a naturally occuring metabolic signaller in human beings
- as a byproduct of anaerobic decomposition of sulfur-containing bio-waste
- Toxicity alarm at 10ppm, toxic at 300-350ppm
- Explosive in air at 4.3-46%, autoignition 232°C
- directly from sulfur and hydrogen at 450°C
- S8(l) + 8 H2(g) → 8 H2S(g)
- from combining sulfuric acid and iron sulfide
- H2SO4(l) + FeS(s) → FeSO4(s) + H2S(g)
- from water on barium sulfide or aluminum sulfide.
- BaS + H2O → BaO + H2S
- Paper soaked in lead acetate turns dark when exposed to hydrogen sulfide when lead sulfide is formed
- (CH3COO)2Pb(s) + H2S(g) → 2 CH3COOH + 2 PbS(s)
- Hydrogen sulfide passed over wet hematite or ground iron oxides produces iron (II,III) sulfide and water, with the oxygen in the iron oxide being displaced by sulfur.
- Fe3O4 + 4 H2S → Fe3S4 + 4 H2O