Double Salt
A salt containing two different cations or anions that dissociates completely into all its constituent ions in solution.
Formula / equation
e.g. K₂SO₄·Al₂(SO₄)₃·24H₂O
Unit
Dimensionless
In depth
Double salts exist only in the solid state, where the two component salts crystallise together in a fixed ratio. On dissolution they simply release all their ions, so their solutions show the ordinary reactions of each ion present.
Examples in the real world
Potash alum giving K⁺, Al³⁺ and SO₄²⁻ ions; Mohr's salt giving Fe²⁺, NH₄⁺ and sulfate.