English Name: Sulfur
CAS No.：7704-34-9
Other Names: Sulfur, colloidal sulfur, sulfur block.
Physical Properties:
Appearance: Light yellow brittle crystal or powder, with a characteristic odor.
Molecular weight: 32.06
Vapor pressure: 0.13 kPa
Flash point: 207°C
Melting point: 119°C
Boiling point: 444.6°C
Relative density (water=1): 2.0
Element symbol: S
Atomic number: 16
Atomic weight: 32.06
Electron configuration: 3S²3P⁴
Position: Third period, Group ⅥA
Main oxidation states: -2, 0, +2, +4, +6
Covalent radius: 104 pm
Ion radii: S⁻² 184 pm, S⁺⁶ 30 pm
First ionization energy: 1000 kJ/mol
Electronegativity: 2.5
Solubility: Insoluble in water, slightly soluble in ethanol and ether, highly soluble in carbon disulfide.
Agricultural Pest Control
Processed into colloidal suspensions for safe, low-phytotoxicity pest management.
Multi-functional agent: Exhibits bactericidal, miticidal, and insecticidal properties.
Used against powdery mildew and leaf beetles in crops, with a residual effect lasting about two weeks.
Example: For powdery mildew control in cucumbers, melons, and pumpkins, dilute 50% sulfur colloidal suspension to 200-400 times and spray. Apply every 10 days: 2 applications for mild infections, 3 for severe cases.
Pharmaceutical and Medicinal Applications
Applied as a powder or via smoke fumigation for genital itching.
Mechanism: Reacts with skin secretions to form hydrogen sulfide and pentathionic acid, which kill mites, fungi, and cause hair depilation.
A mineral with acidic, warm properties and low toxicity; acts on the kidney and large intestine meridians in traditional Chinese medicine.
Topical uses: Kills parasites and relieves itching for scabies, eczema, and skin pruritus.
Industrial significance: Insoluble sulfur becomes a key vulcanizing agent for radial tires (replacing bias tires in transportation), gaining prominence in tire manufacturing.
Disinfection and Sterilization
Sublimed sulfur (flowers of sulfur): Forms sulfides upon contact with skin/tissue secretions, softening skin and exerting bactericidal effects.
Precipitated sulfur (milk of sulfur): Generates hydrogen sulfide and pentathionic acid on skin contact, providing antibacterial and scabicidal actions.
Laxative Effect
Inert in its native form, sulfur converts to sulfides and hydrogen sulfide (H₂S) in the gut.
H₂S stimulates gastrointestinal mucosa, enhancing peristalsis and inducing laxative effects, requiring an alkaline environment, E. coli, and lipolytic enzymes.
Caution: High H₂S concentrations in air can paralyze central nervous system cells and be fatal.
Safety Note: Sulfur is flammable and releases toxic sulfur dioxide when burned. Proper ventilation and protective equipment are essential during handling.