Copper sulphate (CuSO₄) is a salt formed from a weak base (copper(II) hydroxide, Cu(OH)₂) and a strong acid (sulfuric acid, H₂SO₄). When such a salt dissolves in water, the cation from the weak base reacts with water molecules. This reaction, called hydrolysis, produces the weak base and releases hydronium ions (H₃O⁺), making the solution acidic: Cu²⁺(aq) + 2H₂O(l) ⇌ Cu(OH)₂(s) + 2H⁺(aq) or Cu²⁺(aq) + H₂O(l) ⇌ [Cu(OH)]⁺(aq) + H⁺(aq) The sulfate ion (SO₄²⁻) from the strong acid is a very weak conjugate base and does not hydrolyze significantly.