Sulfur Trioxide & Sulfuric Acid

CAS ID #: 7446-11-9, 7664-93-9

Affected Organ Systems: Dermal (Skin), Respiratory (From the Nose to the Lungs)

Cancer Classification: NTP: Known to be a human carcinogen

Please contact NTP, IARC, or EPA’s IRIS Hotline with questions on cancer and cancer classification.

Chemical Classification: None

Summary: Sulfur trioxide (SO3) is generally a colorless liquid. It can also exist as ice- or fiber-like crystals or as a gas. When SO3 is exposed to air, it rapidly takes up water and gives off white fumes. It can react with water to form sulfuric acid. SO3 is also called sulfuric oxide and sulfuric anhydride. It is used in the production of sulfuric acid and other chemicals, and explosives. Sulfuric acid is a clear, colorless, oily liquid that is very corrosive. It is also called sulphine acid, battery acid, and hydrogen sulfate. It is used in the manufacture of fertilizers, explosives, other acids, and glue; in the purifiction of petroleum; in the pickling of metal; and in lead-acid batteries (used in most vehicles).