Material Safety Data Sheet (MSDS) – Silicotungstic Acid

Identification

Product Name: Silicotungstic Acid
Chemical Formula: H4[SiW12O40]·nH2O
Synonyms: Tungstosilicic Acid, Dodecatungstosilicic Acid
CAS Number: 12027-43-9
Use: Catalyst in chemical reactions, laboratory reagent, water treatment processes, research applications
Manufacturer Contact: Safety officer, local distributor, or designated company address and emergency telephone number
Recommended Restriction: For industrial users and research professionals familiar with handling corrosive chemicals

Hazard Identification

GHS Classification: Corrosive to metals (Category 1), Acute toxicity oral (Category 4), Skin corrosion/irritation (Category 1B), Serious eye damage/eye irritation (Category 1)
Signal Word: Danger
Hazard Statements: Causes severe skin burns and eye damage, harmful if swallowed, corrosive to respiratory tract, can cause irritation to mucous membranes upon exposure
Pictograms: Corrosion, Exclamation mark
Precautionary Statements: Avoid breathing dust or mist, do not eat or drink or smoke when using, wash thoroughly after handling, wear impervious gloves, eye protection, face mask, avoid skin, eyes, and clothing contact, use only with adequate ventilation

Composition / Information on Ingredients

Chemical Name: Silicotungstic Acid
CAS Number: 12027-43-9
Concentration: 95-100% (varies with hydration state)
Impurities: May contain trace amounts of other metal oxides and hydrates depending on commercial grade

First Aid Measures

Eye Contact: Rinse eyes gently but thoroughly for 15-20 minutes with clean, lukewarm water, lifting upper and lower eyelids occasionally, seek medical attention without delay
Skin Contact: Remove contaminated clothing, wash affected area with plenty of water and soap, seek medical help for persistent irritation or burns
Inhalation: Move person to fresh air away from exposure source, assist breathing if needed, get immediate medical advice if respiratory symptoms develop
Ingestion: Rinse mouth thoroughly, never give anything by mouth to an unconscious person, do not induce vomiting, get to a healthcare facility or toxicology center right away

Fire-Fighting Measures

Suitable Extinguishing Media: Use water spray, foam, dry chemical, or carbon dioxide
Specific Hazards: Non-combustible, but during heating may release hazardous tungsten or silicon oxides, acidic vapors
Firefighter Instructions: Wear self-contained breathing apparatus and full fire protective clothing, move containers away from fire location if safe, cool exposed containers with water
Hazardous Combustion Products: Tungsten trioxide, silicon dioxide fumes, possible decomposition acids

Accidental Release Measures

Personal Precautions: Isolate spill area, restrict unnecessary entry, ensure proper ventilation, wear protective PPE including gloves, eye/face shields, chemical apron
Environmental Precautions: Prevent chemical runoff into drains, surface waters or soil, use diking to contain large spills
Cleanup Methods: Absorb spills with sand, diatomite, or inert absorbent material, collect and store in appropriate labeled containers, clean area with water using non-metal tools
Decontamination: Wash affected area thoroughly, dispose of cleaning material safely in accordance with regulatory standards

Handling and Storage

Handling: Work in a chemical fume hood or well-ventilated space, use tools and PPE to minimize contact, wash hands and exposed skin before eating or drinking
Storage: Store in tightly closed containers made of compatible acid-resistant material, keep in cool, dry, well-ventilated area, segregate from alkalis, strong bases, reducing agents, moisture-sensitive supplies
Incompatible Materials: Avoid contact with alkali metals, strong bases, organic materials, combustibles, reactive metals that may corrode or react violently

Exposure Controls and Personal Protection

Exposure Limit Values: No official workplace exposure limits, minimize routine exposure as with other strong inorganic acids
Engineering Controls: Use local exhaust, mechanical ventilation, or chemical fume hood
Personal Protective Equipment: Chemical splash goggles, acid-resistant gloves (nitrile, neoprene), lab coats, chemical apron, face shield for large volumes, NIOSH/MSHA certified respirator in non-ventilated settings
Hygiene Measures: Do not eat, drink, or smoke while handling, change contaminated clothing, practice strict industrial hygiene
Monitoring: Regular checks for airborne particulates or surface contamination in high-use environments

Physical and Chemical Properties

Appearance: White-yellow solid or crystalline powder
Odor: Odorless
pH (1% solution): Estimated pH <1 (strong acid)
Melting Point: Decomposes before melting
Boiling Point: Not applicable (decomposes)
Relative Density: About 3.1–3.6 g/cm³ (varies with hydration)
Solubility: Soluble in water, sparingly soluble in most organic solvents
Partition Coefficient: Not determined
Vapor Pressure: Not applicable
Evaporation Rate: Not applicable
Flash Point: Non-flammable
Other Properties: Stable under recommended storage and handling conditions, may become hygroscopic when exposed to humidity

Stability and Reactivity

Chemical Stability: Stable under normal storage, sensitive to moisture, can hydrolyze
Reactivity: Corrosive with many metals, reacts with bases, strong oxidizing agents, and organics
Hazardous Reactions: Intense heat or reaction when in contact with alkalis or reactive metals
Decomposition Products: Tungsten and silicon oxides, acidic fumes when heated or exposed to fire
Polymerization: Does not occur

Toxicological Information

Routes of Exposure: Inhalation, ingestion, skin contact, eye contact
Acute Effects: Harmful if swallowed, severe tissue destruction on skin or eye contact, respiratory tract burns on inhalation
Chronic Effects: Prolonged or repeated exposure can cause tissue scarring, persistent irritation, possible respiratory tract damage
Toxicity Data: No definitive LD50 for humans, studies indicate oral LD50 in rats above 200 mg/kg for similar silicotungstate compounds
Sensitization: No data supporting sensitization documented for this compound
Carcinogenicity: No known carcinogenic effect for silicotungstic acid, not listed by ACGIH, IARC, NTP

Ecological Information

Environmental Impact: Mobilizes heavy metals, can increase acidity of aquatic and terrestrial ecosystems
Aquatic Toxicity: Limited data for silicotungstic acid, related tungstate compounds toxic to some aquatic life at high concentrations
Persistence and Degradability: Inorganic acid, not biodegradable, persists in water and soil as ions and mineral complexes
Bioaccumulation Potential: Tungstate ions can bioaccumulate in aquatic organisms
Other Negative Effects: Reduces surface water quality and can contribute to acidification in unmanaged releases

Disposal Considerations

Waste Disposal Method: Collect as hazardous waste in labeled, acid-resistant containers
Treatment: Neutralize cautiously before disposal if regulations allow, or turn over to licensed chemical waste contractor
Regulatory Disposal Code: Consult local, regional, and national legislation, usually subject to strict waste disposal controls under environmental law
Contaminated Packaging: Treat packaging as hazardous, rinse and dispose of following relevant chemical waste regulations
Do Not: Discharge directly to sewers, soil, groundwater, or bodies of water without pretreatment

Transport Information

UN Number: UN3264
Proper Shipping Name: Corrosive liquid, acidic, inorganic, n.o.s. (contains Silicotungstic Acid)
Transport Hazard Class: 8 (Corrosive substances)
Packing Group: II
Label Requirements: Corrosive hazard symbol
Special Precautions: Secure all containers, avoid transport with incompatible materials, keep upright to prevent leaks or spills, comply fully with international and local regulations for dangerous goods transport

Regulatory Information

TSCA Status: Listed
OSHA Regulation: Classified hazardous under OSHA Hazard Communication Standard
SARA Title III Sections 302/304: Not listed as an extremely hazardous substance
SARA Title III Section 313: Not listed as a toxic chemical
EU Regulations: CLP Regulation EC No 1272/2008 applies, classified as corrosive
REACH Registration: Handled according to REACH framework for laboratory and industrial use
Canada WHMIS: D1B (Toxic material causing immediate and serious toxic effects), E (Corrosive)
Other Inventory Listings: Confirm with country-specific chemical inventories and local workplace safety authorities