Sulfite ion (SO₃²⁻)
- Charge
- −2
- Atoms
- S, O × 3
- Atoms in total
- 4
- Mass of the ion
- 80.057 g/mol
Sulfite is one sulfur atom with three oxygen atoms and a 2− charge. It forms when sulfur dioxide dissolves in water and the resulting sulfurous acid, H₂SO₃, loses both of its hydrogen ions. Sulfites are added to wine and dried fruit as preservatives, and many food labels list them because some people react badly to them.
- The -ite ending shows one oxygen fewer than sulfate, SO₄²⁻, with the same 2− charge.
- Sulfite is easily oxidized to sulfate, which is why it protects foods from oxygen.
- Sodium sulfite, Na₂SO₃, removes dissolved oxygen from boiler water and is used in photographic developers.