Solubility Rules (Edexcel IGCSE Chemistry)
Exam board Pearson Edexcel · IGCSEUpdated 2026-02-10
Spec point —
2.20
Solubility rules
- Ionic compounds are generally soluble in water compared to covalent substances, but there are exceptions
- A knowledge of the solubility of ionic compounds helps us to determine the most appropriate method for the preparation of salts
- The solubility of common ionic compounds is shown below:
Solubility of the common salts
| Salts | Soluble | Insoluble |
|---|---|---|
| Sodium, potassium and ammonium | All | None |
| Nitrates | All | None |
| Chlorides | Most are soluble | Silver and lead(II) |
| Sulfates | Most are soluble | Barium, calcium and lead(II) |
| Carbonates | Carbonates of sodium, potassium and ammonium | Most are insoluble |
| Hydroxides | Hydroxides of sodium potassium and ammonium (calcium hydroxide is sparingly soluble) | Most are insoluble |
- Note that calcium hydroxide is slightly soluble in water
Exam Hint Calcium hydroxide solution is more commonly know as limewater and is used to test for carbon dioxide.
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