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Chemical Name: Ammonium Thiosulfate
Common Uses: Fertilizer in agriculture, photographic fixing agent, industrial water treatment
CAS Number: 7783-18-8
Appearance: Clear to slightly yellowish liquid or crystalline solid, often with a mild odor
Solubility: Highly soluble in water, giving solutions of moderate alkalinity
Odor: Ammonia-like, faint but distinct
Molecular Formula: (NH4)2S2O3
Molecular Weight: 148.21 g/mol
Typical Applications: Agricultural nutrient, auxiliary in photographic labs, metal leaching processes
Acute Exposure: Skin or eye contact can cause mild to moderate irritation; ingestion or inhalation of dust may cause throat or respiratory discomfort
Chronic Exposure: No consistent evidence links normal exposure to long-term toxicity, but repeated skin contact may irritate
Environmental Hazards: Runoff can encourage algae growth in water supplies; too much can disrupt aquatic ecosystems
Fire Hazards: Not flammable, but can decompose under extreme heat, potentially releasing sulfur oxides or ammonia
Personal Risk: Higher risk for those with respiratory conditions or allergies to sulfur or ammonia compounds
Main Ingredient: Ammonium Thiosulfate (typically 56-60% by weight in liquid solutions)
Impurities: Minor ammonium sulfate, trace ammonia, possible sulfite residues
Physical State: Often sold as a concentrated solution, less commonly as a solid
Stabilizers: Occasionally contains anti-caking or anti-corrosive agents, rarely exceeding 1% of total composition
Inhalation: Move to fresh air quickly, monitor for persistent coughing or throat irritation
Skin Contact: Wash exposed area with soap and water, remove soaked clothing
Eye Contact: Rinse thoroughly with clean water for at least fifteen minutes
Ingestion: Rinse mouth, seek medical attention if any discomfort or prolonged symptoms occur
Long-Term Response: Persistent symptoms require medical evaluation, as does accidental swallowing in children
Suitable Extinguishing Media: Standard fire extinguishers (water, foam, dry chemical)
Incompatibilities: Avoid strong acids or strong oxidizers during firefighting
Combustion Products: Possible production of sulfur oxides and ammonia gases, which can be irritating or toxic
Protective Equipment: Firefighters should use self-contained breathing apparatus due to possible release of ammonia and sulfur-containing gases under heat
Explosion Risk: Product does not support combustion, no explosive hazard under normal handling, but sealed containers may burst if heated excessively
Containment: Use dikes or absorbent material like sand to stop liquid from reaching drains
Cleanup: Collect spill using non-metallic tools, avoid creating dust
Environmental Precaution: Keep material out of watercourses; prevent large releases from entering soil or stormwater systems
Personal Protection: Wear gloves, goggles, and if indoors, ensure adequate ventilation; respiratory protection if dust or fumes are present
Disposal of Collected Product: Store in clearly marked containers for proper waste treatment rather than washing down the drain
Storage: Keep containers tightly closed, store in a cool, dry, well-ventilated place out of direct sunlight
Temperature Range: Avoid storing above ambient room temperature to reduce decomposition and pressure build-up
Material Compatibility: No contact with strong acids, bases, or oxidizers; store away from incompatible chemicals to avoid reactive incidents
Handling: Always use personal protective equipment, minimize splashing or direct skin contact
Spill Risk Management: Immediately clean up leaks, keep containers off the ground to avoid corrosion
Engineering Controls: Use local exhaust ventilation when handling in bulk or lengthy transfers
Personal Protection: Gloves made from nitrile or rubber; chemical safety goggles for eyes; apron or long sleeves to protect skin
Inhalation Risk: Suitable dust mask or respirator if high dust or vapor levels exist
Workplace Monitoring: Regularly test air quality in confined spaces, especially for ammonia; have eyewash stations and showers accessible
Hygiene Measures: Wash hands thoroughly after use, do not eat or drink where exposure risk is high
State: Liquid solutions most common; solid form available but less frequently used
Color: Clear to pale yellow
Odor: Slight ammoniacal smell
Boiling Point: Varies with solution strength, typically below 100°C for concentrated solutions
Melting Point: Solid decomposes before melting; liquid may crystallize at low temperatures
Density: About 1.3-1.4 g/cm3 for standard liquid solution
Solubility: Readily dissolves in water, creating alkaline solutions
pH: Typically mild alkaline range, often 8–9 in standard solutions
Chemical Stability: Stable under normal use but can decompose with heat or if allowed to contact strong acids
Thermal Decomposition: Can release ammonia, sulfur dioxide, or hydrogen sulfide gases
Incompatible Materials: Strong oxidizers, acids, and certain metals or salts
Polymerization: Will not undergo hazardous polymerization
Conditions to Avoid: Excess heat, acid contact, and direct sunlight accelerate breakdown and may build dangerous gas pressure
Acute Toxicity: Low likelihood of serious poisoning under typical use, but swallowing large quantities can cause gastrointestinal upset
Chronic Effects: No strong evidence links prolonged low-level exposure to major health hazards, yet direct continuous skin contact can lead to dermatitis
Sensitization: Rare cases of skin or eye sensitization in people with chemical allergies
Carcinogenicity: Not classified as carcinogenic by recognized agencies
Irritation: Direct contact with eyes or mucous membranes may sting or cause redness
Aquatic Toxicity: Can contribute nitrogen and sulfur to water, fostering algae growth and lowering oxygen levels
Persistence and Degradability: Breaks down in soil and water; excessive application risks eutrophication
Bioaccumulation: No significant evidence for buildup in aquatic organisms
Mobility in Soil: Moves readily with water; improper soil application may lead to leaching and runoff
Long-term Impact: Frequent over-application in agriculture threatens waterways, so careful fertilizer management is key
Preferred Method: Use remaining product as intended in accordance with environmental guidelines
Container Disposal: Rinse thoroughly prior to recycling or disposal per local rules
Restricted Disposal: Do not dump in storm drains or sewers; spills in quantity require consultation with local environmental authorities
Waste Handling: Collect any waste evenly and dispose of in approved chemical waste facilities, not in regular trash
Environmental Protection: Responsible users avoid large-scale dumping and monitor for potential runoff hazards
Shipping Classification: Not considered hazardous for ground, air, or sea transport under most international guidelines
Packing Method: Leak-proof containers, capped tightly to prevent spills during transit
Special Precautions: Secure containers upright in trucks; keep away from acids and food items
Spill Risk During Transport: Clean small leaks promptly; for major transit accidents, notify authorities and restrict access
Labeling: Clearly mark product as containing ammonium thiosulfate and list hazard warnings for handlers
Safety Standards: Recognized by agencies for safe use with proper precautions; guidance exists for agricultural and industrial workers
Reporting: Large releases require immediate environmental notification under most regional laws
Occupational Exposure Limits: No binding exposure limit for ammonium thiosulfate itself, but ammonia-related limits may apply
Packaging Requirements: Containers must withstand normal shipping and storage, with chemical-resistant lining as appropriate
Use Restrictions: No special license required for use in agriculture, but industrial use may trigger additional local regulations
