ZnSO₄(aq) → Zn²⁺(aq) + SO₄^2–(aq)

KOH(aq) → K⁺(aq) + OH^–(aq)

Zn²⁺(aq) + 4 OH^–(aq) → ← Zn(OH)₄^2–(aq)

If there is insufficient potassium hydroxide present, the reaction may be:

ZnSO₄(aq) + 2 KOH(aq) → Zn(OH)₂(s) + 2 K⁺(aq) + SO₄^2–(aq)