📖 Theory & Concepts ▼

What are Double Salts?

Compounds containing two different cations or anions that exist only in crystalline form. In solution, they dissociate into constituent ions.

Mohr's Salt

FeSO₄·(NH₄)₂SO₄·6H₂O

Light green crystals, stable to air oxidation

Potash Alum

K₂SO₄·Al₂(SO₄)₃·24H₂O

White octahedral crystals, used in purification

Double Salt vs Complex

  • Double Salt: Loses identity in solution (gives all ions)
  • Complex: Retains identity (complex ion stays intact)
Preparation Method:

Mix equimolar solutions of component salts, concentrate, and crystallize. Cool slowly for good crystal formation.

Select a Salt to Begin

1️⃣
Dissolve
Dissolve salts in water
2️⃣
Mix
Combine solutions
3️⃣
Concentrate
Heat to reduce volume
4️⃣
Crystallize
Cool for crystal formation
Reaction Vessel
Waiting...

Observations

Select Mohr's salt or Potash alum...