Sulfurous acid

Properties

General
Name	Sulfurous acid
Chemical formula	H2SO3
Appearance	Clear, colorless solution with a sulfurous odor.
Physical
Formula weight	82.07 amu
Density	1.03 ×103 kg/m3 (in aqueous solution)
Solubility	Very soluble
Safety
Ingestion	Severe and permanent damage may result.
Inhalation	Causes irritation of the respiratory tract
Skin	Causes burns.
Eyes	Causes burns.
More info	Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references

Sulfurous acid (British English: Sulphurous), also known as sulfur dioxide solution, H₂SO₃, is a mineral acid (not an organic acid), formed when sulfur dioxide dissolves in water. It is a strong reducing agent, and is used to bleach materials that may be damaged by chlorine. In the atmosphere, sulfurous acid may form when sulfur dioxide dissolves in rain drops, causing acid rain.
The compound is only known in aqueous solution and is not isolated in its pure state.