Hydrogen sulfide (H2S)

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Hydrogen sulfide (H2S) Physical and chemical properties: Colorless, toxic gas with a "rotten preserved egg" smell, molecular weight 34.08, melting point: -82.9℃, boiling point: -61.8℃, relative density (air=1): 1.19, saturated vapor pressure: 2026.5kPa (25.5℃), critical temperature: 100.4℃, critical pressure: 9.01MPa, lower explosion limit: 4.3%, explosion limit 45.5%, ignition temperature: 260℃, minimum ignition energy: 0.077mJ, maximum explosion pressure: 0.490Mpa, hazardous characteristics: It can form an explosive mixture when mixed with air, and can cause combustion and explosion when exposed to open flames and high temperatures. Reacts violently with concentrated nitric acid, fuming nitric acid or other strong oxidants, causing an explosion. Hydrogen sulfide is heavier than air and can spread far away from the bottom. It can quickly cause backfire when exposed to an open flame. In addition, it is easily soluble in water, methanol, ethanol, petroleum solvents and crude oil. health hazards: Hydrogen sulfide is a strong neurotoxicant. The main way to invade the human body is inhalation, and poisoning caused by absorption through the human mucous membrane is faster than absorption through the skin. The local irritating effect of hydrogen sulfide on mucous membranes is caused by the sodium sulfide formed after contact with moist mucous membranes and its own acidity. Since the human central nervous system is most sensitive to hypoxia, the first thing to be damaged is the central nervous system. If a person inhales 70 to 150 mg/cubic meter of hydrogen sulfide/1 to 2 hours, symptoms of respiratory tract and eye irritation will occur.: Tears, eye pain, photophobia, blurred vision and runny nose, cough, throat burning, olfactory fatigue after 2 to 5 minutes of inhalation, no longer smelling odor, and becoming numb ； If mg/m3/1 hour is inhaled, acute eye irritation symptoms will occur in 6 to 8 minutes, and longer exposure may cause pulmonary edema. Inhalation of 760 mg/cubic meter/15 to 60 minutes will cause pulmonary edema, bronchitis, pneumonia, dizziness, headache, nausea, vomiting, fainting, fatigue, confusion and other symptoms. ； If 1000 mg/cubic meter is inhaled within a few seconds, acute poisoning will occur quickly, causing sudden coma, respiratory and cardiac arrest, and lightning-type death. Exposure to high concentrations may cause edema and corneal ulcers in the conjunctiva. Long-term exposure to low concentrations can cause neurasthenia syndrome and autonomic nerve dysfunction.