sodium sulfite

chemical compound

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July 13, 2026

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Sodium sulfite is a chemical compound with the formula Na₂SO₃. It is a crystalline salt used as a reducing agent, bleaching agent, and antichlor. It also finds applications in photographic developing and fixing baths, and as a food preservative.1

Sodium sulfite is one of many compounds formed by sodium, which is highly reactive and typically has an oxidation state of +1. While pure sulfurous acid (H₂SO₃) has not been isolated, its aqueous solutions contain ions that form two series of salts: sulfites (SO₃²⁻) and hydrogen sulfites (HSO₃⁻). Sodium sulfite is an alkali metal sulfite, and unlike many other sulfites, it is relatively soluble. It can be oxidized by air to the more stable sodium sulfate. Sodium bisulfite (NaHSO₃) is another related compound, often formed by passing sulfur dioxide through a sodium carbonate solution.234

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sulfur
Compounds
Its most important salt is sodium sulfite, Na₂SO₃, a reducing agent employed in the manufacture of paper pulp, in photography, and in the removal of oxygen from boiler feedwater. Sulfuric acid is one of the most valuable of all chemicals. Prepared commercially by the reaction of water with sulfur trioxide,…
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Its most important salt is sodium sulfite, Na₂SO₃, a reducing agent employed in the manufacture of paper pulp, in photography, and in the removal of oxygen from boiler feedwater. Sulfuric acid is one of the most valuable of all chemicals. Prepared commercially by the reaction of water with sulfur trioxide,…
Read More