ICSC 1202 - SULFUR TRIOXIDE

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SULFUR TRIOXIDE	ICSC: 1202 (December 2022)
Sulfuric oxide Sulphuric (acid) anhydride

CAS #: 7446-11-9

UN #: 1829

EC Number: 231-197-3

	ACUTE HAZARDS	PREVENTION	FIRE FIGHTING
FIRE & EXPLOSION	Not combustible. Gives off irritating or toxic fumes (or gases) in a fire. Many reactions may cause fire or explosion. Heating will cause rise in pressure with risk of bursting. See Notes. Risk of fire and explosion on contact with bases, combustible substances, reducing agents, water or organic materials.	NO contact with incompatible substances. See Chemical Dangers.	NO water. In case of fire in the surroundings, use appropriate extinguishing media. In case of fire: keep drums, etc., cool by spraying with water. NO direct contact with water.

PREVENT GENERATION OF MISTS! AVOID ALL CONTACT! IN ALL CASES CONSULT A DOCTOR!
	SYMPTOMS	PREVENTION	FIRST AID
Inhalation	Cough. Sore throat. Burning sensation. Shortness of breath. Laboured breathing.	Use ventilation, local exhaust or breathing protection.	Fresh air, rest. Half-upright position. Artificial respiration may be needed. Refer immediately for medical attention.
Skin	Redness. Pain. Blisters. Serious skin burns.	Protective gloves. Protective clothing. Apron.	Wear protective gloves when administering first aid. First rinse with plenty of water for at least 15 minutes, then remove contaminated clothes and rinse again. Refer immediately for medical attention .
Eyes	Redness. Pain. Severe burns.	Wear face shield or eye protection in combination with breathing protection.	Rinse with plenty of water for several minutes (remove contact lenses if easily possible). Refer immediately for medical attention.
Ingestion	Burns in mouth and throat. Burning sensation behind the breastbone. Abdominal pain. Vomiting. Shock or collapse.	Do not eat, drink, or smoke during work.	Rinse mouth. Give nothing to drink. Do NOT induce vomiting. Refer immediately for medical attention.

SPILLAGE DISPOSAL	CLASSIFICATION & LABELLING
Evacuate danger area! Consult an expert! Personal protection: chemical protection suit including self-contained breathing apparatus. Do NOT let this chemical enter the environment. Do NOT wash away into sewer. Ventilation. Collect leaking liquid in covered containers. Absorb remaining liquid in dry sand or inert absorbent. Do NOT absorb in saw-dust or other combustible absorbents. Then store and dispose of according to local regulations.	According to UN GHS Criteria Causes severe skin burns and eye damage May cause respiratory irritation May be corrosive to metals See Notes Transportation UN Classification UN Hazard Class: 8; UN Pack Group: I
STORAGE
Refer to the manufacturer's instructions for proper storage conditions. Dry. Well closed. Store only in original packaging. Separated from food and feedstuffs and incompatible materials. See Chemical Dangers. Store only if stabilized.
PACKAGING
Airtight. Unbreakable packaging. Put breakable packaging into closed unbreakable container. Do not transport with food and feedstuffs.

SULFUR TRIOXIDE

ICSC: 1202

PHYSICAL & CHEMICAL INFORMATION
Physical State; Appearance HYGROSCOPIC LIQUID OR SOLID IN VARIOUS FORMS. (SEE NOTES). Physical dangers The vapour is heavier than air. Chemical dangers The substance is a strong oxidant. It reacts violently with combustible and reducing materials and organic compounds. This generates fire and explosion hazard. Reacts violently with water and moist air. This produces sulfuric acid. This generates heat and fire or explosion hazard. The solution in water is a strong acid. It reacts violently with bases and is corrosive to metals. This produces flammable/explosive gas (hydrogen - see ICSC 0001). See Notes.	Formula: SO₃ Molecular mass: 80.1 Boiling point: 44.8°C Melting point: 17°C Relative density (water = 1): 1.9 Solubility in water: violent reaction Vapour pressure, kPa at 25°C: 57.7 Relative vapour density (air = 1): 2.8 Relative density of the vapour/air-mixture at 20°C (air = 1): 1.2-2 See Notes.

PHYSICAL & CHEMICAL INFORMATION

Physical State; Appearance
HYGROSCOPIC LIQUID OR SOLID IN VARIOUS FORMS. (SEE NOTES).

Physical dangers
The vapour is heavier than air.

Chemical dangers
The substance is a strong oxidant. It reacts violently with combustible and reducing materials and organic compounds. This generates fire and explosion hazard. Reacts violently with water and moist air. This produces sulfuric acid. This generates heat and fire or explosion hazard. The solution in water is a strong acid. It reacts violently with bases and is corrosive to metals. This produces flammable/explosive gas (hydrogen - see ICSC 0001). See Notes.

Formula: SO₃
Molecular mass: 80.1
Boiling point: 44.8°C
Melting point: 17°C
Relative density (water = 1): 1.9
Solubility in water: violent reaction
Vapour pressure, kPa at 25°C: 57.7
Relative vapour density (air = 1): 2.8
Relative density of the vapour/air-mixture at 20°C (air = 1): 1.2-2
See Notes.

EXPOSURE & HEALTH EFFECTS
Routes of exposure Serious local effects by all routes of exposure. The substance can be absorbed into the body by inhalation of its vapour. Effects of short-term exposure The substance is very corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion. Exposure could cause asphyxiation due to swelling in the throat. Inhalation of high concentrations may cause lung oedema, but only after initial corrosive effects on the eyes and the upper respiratory tract have become manifest. Inhalation may cause asthma-like reactions (RADS). Medical observation is indicated. See Notes.	Inhalation risk A harmful contamination of the air will be reached very quickly on evaporation of this substance at 20°C. Effects of long-term or repeated exposure Repeated or prolonged inhalation of the aerosol may cause effects on the lungs. Risk of tooth erosion upon repeated or prolongated exposure to an aerosol of this substance. Mists of this strong inorganic acid are carcinogenic to humans. See Notes.

EXPOSURE & HEALTH EFFECTS

Routes of exposure
Serious local effects by all routes of exposure. The substance can be absorbed into the body by inhalation of its vapour.

Effects of short-term exposure
The substance is very corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion. Exposure could cause asphyxiation due to swelling in the throat. Inhalation of high concentrations may cause lung oedema, but only after initial corrosive effects on the eyes and the upper respiratory tract have become manifest. Inhalation may cause asthma-like reactions (RADS). Medical observation is indicated. See Notes.

Inhalation risk
A harmful contamination of the air will be reached very quickly on evaporation of this substance at 20°C.

Effects of long-term or repeated exposure
Repeated or prolonged inhalation of the aerosol may cause effects on the lungs. Risk of tooth erosion upon repeated or prolongated exposure to an aerosol of this substance. Mists of this strong inorganic acid are carcinogenic to humans. See Notes.

OCCUPATIONAL EXPOSURE LIMITS

ENVIRONMENT
The substance is harmful to aquatic organisms.

NOTES
The substance is liquid or solid, depending on the composition. The alpha- and beta-forms appear as asbestos-like needles. Molten sulfur trioxide exists only in the gamma-form and condenses when cooling down forming solid, ice-like gamma-sulfur trioxide. This slowly converts to alpha- and beta-sulfur trioxide when stored for a long time. When the alpha form melts it takes the gamma form, and vapor pressure rises dramatically with a hazard of explosion. Boiling point is for the gamma form. Other melting points: 62°C (alpha form), 33°C (beta form), 17°C (gamma form). Vapour pressure is 9.7, 45.9 and 57.7 kPa at 25°C for alpha, beta and gamma forms. NEVER pour water into this substance; when dissolving or diluting always add it slowly to the water. The symptoms of lung oedema often do not become manifest until a few hours have passed and they are aggravated by physical effort. Rest and medical observation are therefore essential. IARC considers mists of strong inorganic acid to be carcinogenic (group 1). However there is no information available on the carcinogenicity of other physical forms of this substance. Therefore no classification for carcinogenicity under GHS has been applied.

NOTES

The substance is liquid or solid, depending on the composition. The alpha- and beta-forms appear as asbestos-like needles. Molten sulfur trioxide exists only in the gamma-form and condenses when cooling down forming solid, ice-like gamma-sulfur trioxide. This slowly converts to alpha- and beta-sulfur trioxide when stored for a long time.
When the alpha form melts it takes the gamma form, and vapor pressure rises dramatically with a hazard of explosion.
Boiling point is for the gamma form.
Other melting points: 62°C (alpha form), 33°C (beta form), 17°C (gamma form).
Vapour pressure is 9.7, 45.9 and 57.7 kPa at 25°C for alpha, beta and gamma forms.
NEVER pour water into this substance; when dissolving or diluting always add it slowly to the water.
The symptoms of lung oedema often do not become manifest until a few hours have passed and they are aggravated by physical effort. Rest and medical observation are therefore essential.
IARC considers mists of strong inorganic acid to be carcinogenic (group 1). However there is no information available on the carcinogenicity of other physical forms of this substance. Therefore no classification for carcinogenicity under GHS has been applied.

ADDITIONAL INFORMATION

EC Classification

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