Sulfur trioxide

Description

Sulfur trioxide · CAS 7446-11-9 · O3S. UNII HH2O7V4LYD. Boiling Point: 44.8 °C; Melting Point: 62.2 °C; Melting Point: 17 °C.

Identification

CAS Registry Number	7446-11-9
PubChem CID	24682
Molecular formula	O3S
IUPAC name	sulfur trioxide
UNII (FDA)	HH2O7V4LYD

Computed Descriptors

Molecular Weight	80.07
XLogP3	-0.5
Hydrogen Bond Donor Count	0
Hydrogen Bond Acceptor Count	3
Rotatable Bond Count	0
Exact Mass	79.95681503
Monoisotopic Mass	79.95681503
Topological Polar Surface Area	52.2
Heavy Atom Count	4
Formal Charge	0

Physical & Chemical Properties

Boiling Point	44.8 °C
Melting Point	62.2 °C
Melting Point	17 °C
Vapor Density	2.76 (Air = 1)
Vapor Pressure	263.0 [mmHg]
Heat of Vaporization	43.14 kJ/mol at 25 °C

Physical description & handling notes

• Colorless to white solid that fumes in air at room temperature; [HSDB] Exists in 3 modifications; The alpha and beta forms are solids; mp = 62.3 and 32.5 deg C, respectively; The gamma form is a solid or liquid with a mp of 16.8 deg C; [Merck Index]
• HYGROSCOPIC LIQUID OR SOLID IN VARIOUS FORMS. .
• White needles
• Asbestos-like needles
• Pure sulfur trioxide is a colorless liquid that fumes in air at room temperature and pressure.
• 113 °F at 760 mmHg all forms (EPA, 1998)

Regulatory Status

GHS notification summary	14.9% (75 / 503)

GHS Hazard Classification

GHS notification summary	14.9% (75 / 503)
Reported hazard statements	H314 (85.1%), H318 (49.3%), H330 (16.1%), H335 (79.9%), H351 (11.3%), H411 (11.3%)

Documented Uses

• Used as a sulfonating agent in the production of detergents and an intermediate in the production of sulfuric acid and explosives; [HSDB]
• Intermediate in sulfuric acid manufacture; in sulfonations for formation of addition cmpd with amines; in the manufacture of explosives
• Sulfonation of organic compounds, especially nonionic detergents, solar energy collectors.
• Production of detergents, as a raw material for chlorosulfuric acid and 65% oleum. Has been added to cooled combustion gases at many coal burning power plants to improve dust removal in electrostatic precipitators.
• Sulfur trioxide is used as such for preparing sulfonated oils, and alkyl arenesulfonate detergents.
• ... Used as a powerful, but generally indiscriminate oxidizing agent, however, it will selectively oxidize pentachlorotoluene and similar compounds to the alcohol.

Synonyms

SULFUR TRIOXIDE; 7446-11-9; Sulphur trioxide; Sulfur oxide (SO3); HH2O7V4LYD; DTXSID1029673; CHEBI:29384; Sulfan; Sulfuric oxide; RefChem:6276; Sulfur trioxide, stabilized; DTXCID409673; 231-197-3; Sulfuric anhydride; Sulfite radical anion; Sulfur trioxide, contains stabilizer, >=99%

Frequently Asked Questions

What are the CAS number and molecular formula of Sulfur trioxide?

CAS 7446-11-9; molecular formula O3S; molecular weight — g/mol.

What other names is Sulfur trioxide known by?

SULFUR TRIOXIDE, 7446-11-9, Sulphur trioxide, Sulfur oxide (SO3), HH2O7V4LYD, DTXSID1029673.

Is Sulfur trioxide classified as hazardous?

14.9% of GHS notifications report no hazard classification (75 of 503).

What are the key physical properties of Sulfur trioxide?

Boiling Point: 44.8 °C; Melting Point: 62.2 °C; Melting Point: 17 °C; Vapor Density: 2.76 (Air = 1).

Facts on this page are taken from PubChem (US National Library of Medicine) and Wikidata. Grade-specific data — assay, moisture, particle size, packaging, shelf life — is issued per batch on the COA and is not published here.