* Sodium sulfate's formula is Na₂SO₄. This tells us there are two sodium ions (Na⁺) and one sulfate ion (SO₄²⁻) in each formula unit.

* When sodium sulfate dissolves in water, it dissociates into its ions:

Na₂SO₄ (s) → 2 Na⁺ (aq) + SO₄²⁻ (aq)

* Therefore, three ions are made when one formula unit of sodium sulfate dissolves in water.