Sulfurous acid

Sulfurous acid is a chemical compound with the formula H2SO3. It is a weak acid that is formed when sulfur dioxide is dissolved in water. It is not usually isolated in its pure form but is primarily used in the preparation of other sulfur-containing compounds.

Chemical Properties

Sulfurous acid is a clear, colorless liquid that is highly soluble in water. It is a weak acid, meaning it only partially ionizes in solution. The acid is unstable and tends to decompose into water and sulfur dioxide. It can act as a reducing agent and can be oxidized to sulfuric acid.

Preparation

Sulfurous acid is typically prepared by dissolving sulfur dioxide in water. This reaction is exothermic, meaning it releases heat. The resulting solution contains a mixture of sulfurous acid and its conjugate base, the bisulfite ion.

Uses

Sulfurous acid is primarily used in the preparation of other sulfur-containing compounds. It is used in the production of sulfites, which are used as preservatives in food and beverages. It is also used in the production of detergents, paper, and textiles.

Safety

Exposure to sulfurous acid can cause irritation to the eyes, skin, and respiratory tract. It is considered a hazardous substance and should be handled with care.

See Also

• Sulfuric acid
• Sulfur dioxide
• Sulfites