Sulfite

Sulfite is the polyatomic ion SO₃²⁻, consisting of sulfur and three oxygen atoms with an overall charge of −2. The name also applies to salts containing this ion.

Sulfurous acid: The name conventionally given to aqueous sulfur dioxide and its acid–base forms, including hydrogen sulfite and sulfite. Sulfite is the fully deprotonated form in sulfurous acid’s conventional acid–base sequence.
Food preservative: A substance added to food to slow spoilage or preserve desired qualities. Sulfites are used as preservatives and antioxidants in some foods and drinks.
Polyatomic ion: A charged group of two or more covalently bonded atoms that behaves as a unit in chemical reactions. Sulfite is a polyatomic ion with a net charge of −2.
Sodium sulfite: The ionic compound Na₂SO₃, a water-soluble sulfite salt used as a reducing agent and preservative. It is a common, readily soluble example of a sulfite salt.
Hydrogen sulfite: The ion HSO₃⁻, formed when sulfurous acid loses one proton or sulfite gains one. It interconverts with sulfite as solution acidity changes.
Wine: An alcoholic beverage made by fermenting grape juice or other fruit juice. Winemaking uses sulfites to limit oxidation and microbial growth.
Sulfur: A nonmetallic chemical element with atomic number 16, found in many minerals and biological molecules. Sulfur is the central atom in the sulfite ion.
Potassium sulfite: The ionic compound K₂SO₃, a water-soluble salt containing potassium ions and sulfite ions. It illustrates how sulfite forms salts with different metal cations.
Sulfate: The polyatomic ion SO₄²⁻, containing sulfur and four oxygen atoms with an overall charge of −2. Sulfate is the more oxidized sulfur oxyanion often formed when sulfite reacts with oxygen.
Dried fruit: Fruit preserved by removing much of its water through drying. Sulfites are used on some dried fruits to slow browning and preserve color.

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