Hydrogen sulfide

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Hydrogen sulfide
Chemical formula H2S
OTP appearance colorless gas 
Molar Mass(g/mol) 34.1 
Melting Point(°C) -82 
Boiling Point(°C) -60 
Density(g/cc) 0.001363 
Fuel Value(MJ/kg) 17.65 
Immediate Danger to Life and Health 100ppm
NFPA 704
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Hydrogen sulfide is a toxic gas evolved from and involved with a variety of processes. Heavier than air.

Uses

Primary

  • used to precipitate certain metal ions (Pb,Cu,Hg,As) in solution:

Secondary

  • Source of sulfur via the Clause Process:
2 H2S + 3 O2 2 SO2 + 2 H2O
4 H2S + 2 SO2 3 S2 + 4 H2O

Natural occurrence

  • as a naturally occuring metabolic signaller in human beings
  • as a byproduct of anaerobic decomposition of sulfur-containing bio-waste

Hazards

  • Toxicity alarm at 10ppm, toxic at 300-350ppm
  • Explosive in air at 4.3-46%, autoignition 232°C

Character

Synthesis

Purification

Testing

Detection

  • 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)

Storage

Disposal

  • 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

See Also

References