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SULFUR TRIOXIDE ICSC: 1202
Date of Peer Review: October 2002

Sulphuric (acid) anhydride
Sulfuric oxide
CAS # 7446-11-9 SO3
RTECS # WT4830000 Molecular mass: 80.1
UN # 1829
EC #
TYPES OF HAZARD / EXPOSURE ACUTE HAZARDS / SYMPTOMS PREVENTION FIRST AID / FIRE FIGHTING
FIRE Not combustible. Heating will cause rise in pressure with risk of bursting. Gives off irritating or toxic fumes (or gases) in a fire.
NO contact with base(s), combustibles, reducing agents, water.
NO hydrous agents. NO water. In case of fire in the surroundings: use appropriate extinguishing media.
EXPLOSION Risk of fire and explosion on contact with base(s), combustible substances, reducing agents, water.

In case of fire: cool drums, etc., by spraying with water but avoid contact of the substance with water.
EXPOSURE
PREVENT GENERATION OF MISTS! AVOID ALL CONTACT!
IN ALL CASES CONSULT A DOCTOR!
Inhalation Burning sensation. Cough. Laboured breathing. Sore throat. Wheezing. Shortness of breath.
Ventilation, local exhaust, or breathing protection.
Fresh air, rest. Half-upright position. Refer for medical attention.
Skin Redness. Serious skin burns. Pain. Blisters.
Protective gloves. Protective clothing.
Remove contaminated clothes. Rinse skin with plenty of water or shower. Refer for medical attention.
Eyes Redness. Pain. Blurred vision. Severe deep burns.
Face shield, or eye protection in combination with breathing protection.
First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then take to a doctor.
Ingestion Abdominal pain. Burning sensation. Nausea. Shock or collapse.
Do not eat, drink, or smoke during work.
Refer for medical attention. Rinse mouth. Do NOT induce vomiting. Give plenty of water to drink.
SPILLAGE DISPOSAL PACKAGING & LABELLING
Evacuate danger area! Consult an expert! Do NOT absorb in saw-dust or other combustible absorbents. Absorb remaining liquid in dry sand or inert absorbent and remove to safe place. Ventilation. NEVER direct water jet on liquid. Do NOT let this chemical enter the environment. Chemical protection suit including self-contained breathing apparatus.
Do not transport with food and feedstuffs. Airtight.
EU Classification
UN Classification
UN Hazard Class: 8
UN Pack Group: I
EMERGENCY RESPONSE STORAGE
Transport Emergency Card: TEC (R)-80GC1-I-X
NFPA Code: H3; F0; R2;
Store only if stabilized. Separated from food and feedstuffs, incompatible materials. See Chemical Dangers. Dry. Store between 17C and 25C.
IPCS
International
Programme on
Chemical Safety
Prepared in the context of cooperation between the International Programme on Chemical Safety and the Commission of the European Communities IPCS, CEC 1999

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SULFUR TRIOXIDE ICSC: 1202
IMPORTANT DATA
PHYSICAL STATE; APPEARANCE:
FUMING HYGROSCOPIC COLOURLESS LIQUID OR COLOURLESS TO WHITE CRYSTALS

PHYSICAL DANGERS:
The vapour is heavier than air. See Notes.

CHEMICAL DANGERS:
The substance is a strong oxidant and reacts violently with combustible and reducing materials and organic compounds causing fire and explosion hazard. Reacts violently with water and moist air to produce sulfuric acid. The solution in water is a strong acid, it reacts violently with bases and is corrosive metals forming flammable/explosive gas (hydrogen - see ICSC0001).

OCCUPATIONAL EXPOSURE LIMITS:
TLV not established.
ROUTES OF EXPOSURE:
The substance can be absorbed into the body by inhalation of its vapour and by ingestion.

INHALATION RISK:
A harmful contamination of the air will be reached very quickly on evaporation of this substance at 20C.

EFFECTS OF SHORT-TERM EXPOSURE:
The substance is corrosive to the eyes, the skin and the respiratory tract. Corrosive on ingestion.

EFFECTS OF LONG-TERM OR REPEATED EXPOSURE:
Lungs may be affected by repeated or prolonged exposure to an aerosol of this substance. Risk of tooth erosion upon repeated or prolonged exposure to an aerosol of this substance. Strong inorganic acid mists containing this substance are carcinogenic to humans.
PHYSICAL PROPERTIES
Boiling point: 45C
Melting point: see Notes
Relative density (water = 1): 1.9
Solubility in water: reaction
Vapour pressure, kPa at 25C: see Notes
Relative vapour density (air = 1): 2.8
Relative density of the vapour/air-mixture at 20C (air = 1): 1.2-2
ENVIRONMENTAL DATA
The substance is harmful to aquatic organisms.
NOTES
NEVER pour water into this substance; when dissolving or diluting always add it slowly to the water. When the alpha form melts it takes the gamma form, and vapor pressure rises dramatically with a hazard of explosion. Melting point is 62, 33 and 17C for alpha, beta and gamma forms. Vapour pressure is 9.7, 45.9 and 57.7 kPa at 25C for alpha, beta and gamma forms.
ADDITIONAL INFORMATION


LEGAL NOTICE Neither the CEC nor the IPCS nor any person acting on behalf of the CEC or the IPCS is responsible for the use which might be made of this information
IPCS, CEC 1999