7.3 Preparation of Salts

2026 Syllabus Objectives

1. Core: Describe the preparation, separation and purification of soluble salts by reaction of an acid with:

   • (a) an alkali by titration
   • (b) excess metal
   • (c) excess insoluble base
   • (d) excess insoluble carbonate

2. Core: Describe the general solubility rules for salts:

   • (a) sodium, potassium and ammonium salts are soluble
   • (b) nitrates are soluble
   • (c) chlorides are soluble, except lead and silver
   • (d) sulfates are soluble, except barium, calcium and lead
   • (e) carbonates are insoluble, except sodium, potassium and ammonium
   • (f) hydroxides are insoluble, except sodium, potassium, ammonium and calcium (partially)

3. Core: Define a hydrated substance as a substance that is chemically combined with water and an anhydrous substance as a substance containing no water

4. Supplement: Describe the preparation of insoluble salts by precipitation

5. Supplement: Define the term water of crystallisation as the water molecules present in hydrated crystals, including $\text{CuSO}_4 \cdot 5\text{H}_2\text{O}$ and $\text{CoCl}_2 \cdot 6\text{H}_2\text{O}$