Sulfur dioxide

  • Sulfurous anhydride
  • Sulfur oxide
Formula
SO2
Structure
Description
A colorless gas with a choking or suffocating odor.
Uses
Preserving fruits, disinfectant in breweries & food factories.

Registry Numbers and Inventories.
CAS
7446-09-5
EC (EINECS/ELINCS)
231-195-2
EC Index Number
016-011-00-9
EC Class
Toxic; Corrosive
RTECS
WS4550000
RTECS class
Agricultural Chemical and Pesticide; Tumorigen; Mutagen; Reproductive Effector; Human Data; Primary Irritant
UN (DOT)
1079
Merck
12,9144
Beilstein/Gmelin
1443 (G)
EPA OPP
77601
Swiss Giftliste 1
G-2871
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
O2(32)S
Formula mass
64.05
Melting point, °C
-75.7
Boiling point, °C
-10.3
Sublimation point, °C
-165.2
Vapor pressure, mmHg
43.7 (-60 C)
Vapor density (air=1)
2.2
Odor Threshold Odor threshold 0.47 ppm
Critical temperature
157
Critical pressure
77.7
Density
1.434 g/cm3 (20 C)
Solubility in water
8.5 g/100 mL (20 C)
Viscosity
0.0124 cp (18C)
Surface tension
28.59 g/s2 (10 C)
Refractive index
1.3047 (20 C)
Dipole moment
1.634 D
Dielectric constant
22.93 (-61 C)
Thermal expansion
0.003902/K
Heat of fusion
8.6 kJ/mol
Heat of vaporization
25.4 kJ/mol

Hazards and Protection.
Storage
Protect against physical damage, store outdoors or in a well ventilated area of noncombustible construction.
A D1A E
Handling
Containers of this material may be hazardous when emptied. Since emptied containers retain product residues (vapor, liquid, and/or solid), all hazard precautions given in the data sheet must be observed.
Protection
Wear appropriate protective gloves, clothing and goggles.
Respirators
Wear positive pressure self-contained breathing apparatus (SCBA).
Small spills/leaks
Keep material out of water sources and sewers. Attempt to stop leak if without undue personnel hazard. Use water spray to knock-down vapors. Neutralize spilled material with crushed limestone, soda ash, or lime. Do not use water on material itself.
Stability
Stable.
Incompatibilities
Reacts exothermically with bases such as amines, amides, metal oxides, and hydroxides Reacts explosively with fluorine. Avoid ammonia, monocesium or monopotassium acetylide; dicesium monoxide; iron (II) oxide; tin oxide; lead (IV) oxide; chromium; manganese; molten sodium, powder aluminum and rubidium. Sulfur dioxide has explosive properties when it comes in contact with sodium hydride; potassium chlorate at elevated temperatures; ethanol; ether; zinc ethylsulfurinate at very cool temperatures (-15C); fluorine; chlorine trifluoride and chlorates. It will react with water or steam to produce toxic and corrosive fumes.
Decomposition
Sulfur compounds.

Fire.
Fire fighting
Wear self-contained breathing apparatus and full protective clothing. Move container from fire area. Stay away from ends of tanks. Cool containers that are exposed to flames with water from the side until well after the fire is out. Isolate area until gas has dispersed. Keep unnecessary people away.Not flammable. Extinguish fires with dry chemical, carbon dioxide, water spray, fog or foam.
Fire potential
Nonflammable.
Hazards
Containers may explode in heat of fire or they may rupture and release irritating toxic sulfur dioxide. Sulfur dioxide has explosive properties when it comes in contact with sodium hydride; potassium chlorate at elevated temperatures; ethanol; ether; zinc ethylsulfurinate at very cool temperatures (-15C); fluorine; chlorine trifluoride and chlorates. It will react with water or steam to produce toxic and corrosive fumes. When the liquid is heated it may release irritating, toxic sulfur dioxide gas.
Health
3
 
Flammability
0
 
 
Reactivity
0
 

Health.
Exposure limit(s)
OSHA PEL: TWA 5 ppm (13 mg/m3) NIOSH REL: TWA 2 ppm (5 mg/m3) ST 5 ppm (13 mg/m3) NIOSH IDLH: 100 ppm
Poison_Class
3
Exposure effects
Maternal toxicity and embryotoxicity have been observed.
   Ingestion
Nausea, vomiting, and abdominal pain have been reported.
   Inhalation
Vapors are extremely irritating and corrosive.
   Skin
Direct contact with liquefied sulfur dioxide could cause frostbite injury.
   Eyes
See Skin.

First aid
 
   Ingestion
Seek medical assistance.
   Inhalation
Move victim to fresh air. Apply artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; induce artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Effects may be delayed.
   Skin
Rewarming and a variety of topical treatments are indicated for frostbite injury. See main treatment section for more information.
   Eyes
Irrigate exposed eyes with copious amounts of tepid water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist, the patient should be seen in a health care facility.

Transport.
UN number
1079
Response guide
Hazard class
2.3
PRTC
T
USCG CHRIS Code
SFD
 
Std. Transport #
4920508
 
IMO Gas Code
N