Sulfate ion (SO₄²⁻)
- Charge
- −2
- Atoms
- S, O × 4
- Atoms in total
- 5
- Mass of the ion
- 96.056 g/mol
Sulfate is one sulfur atom surrounded by four oxygen atoms, with a 2− charge. It is the ion formed when sulfuric acid, H₂SO₄, gives up both of its hydrogen ions. You meet it in Epsom salt, plaster and drywall, fertilizers, and the barium sulfate drink patients swallow before an X-ray of the gut.
- Sulfate has one more oxygen atom than sulfite, SO₃²⁻, and both carry a 2− charge.
- Adding one H⁺ to sulfate gives hydrogen sulfate, HSO₄⁻, also called bisulfate.
- Epsom salt is magnesium sulfate, MgSO₄, usually sold as the crystal hydrate MgSO₄·7H₂O.