Sulfurous acid, with the chemical formula H₂SO₃, is a weak acid formed when sulfur dioxide (SO₂) dissolves in water. It is characterized by its colorless appearance and a pungent, suffocating odor reminiscent of burnt matches. Sulfurous acid is unstable and typically exists in solution rather than as a pure substance. It acts as a reducing agent and can participate in various chemical reactions, including the formation of sulfites and bisulfites. The acid is known for its ability to act as a preservative and antioxidant in food and beverages. In terms of safety, sulfurous acid can be irritating to the skin, eyes, and respiratory system, necessitating careful handling. Its CAS number is 7782-99-2, although this number is often associated with sulfur dioxide rather than the acid itself, as sulfurous acid is not commonly isolated in pure form. Overall, sulfurous acid plays a significant role in both industrial applications and environmental chemistry, particularly in the context of acid rain and atmospheric processes.

Sulfurous acid

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Sulfurous acid is used as a reducing agent, bleaching agent and disinfectant. It is utilized for bleaching of moistened wool, straw for hats, and other materials injured by chlorine. It finds application as a disinfectant as well as used externally for its parasiticidal effect in various skin diseases. Its derivative viz. sulfites are included in antiseptics, antifermentatives, and antizymotics. This Thermo Scientific Chemicals brand product was originally part of the Alfa Aesar product portfolio. Some documentation and label information may refer to the legacy brand. The original Alfa Aesar product / item code or SKU reference has not changed as a part of the brand transition to Thermo Scientific Chemicals.

CAS 7782-99-2: Sulfurous acid

Sulfurous acid, ACS, 6.0% SO{2} min

Ref: 02-033275