Guides
Solubility Rules: Table & Mnemonics for Salts in Water
To tell whether a salt dissolves in water, use a set of common solubility rules — summarized below as a table.
Quick rules
- All nitrates and all group-1 / ammonium salts are soluble.
- Chlorides/bromides/iodides: soluble except Ag⁺ and Pb²⁺ (PbCl₂ slightly).
- Sulfates: soluble except Ba²⁺, Pb²⁺ (Ca²⁺, Ag⁺ slightly).
- Carbonates & phosphates: insoluble except group-1/ammonium.
- Hydroxides: insoluble except group-1, Ba(OH)₂ (Ca(OH)₂ slightly).
Rule table (by anion)
| Anion | Rule |
|---|---|
| NO₃⁻ nitrate | All soluble |
| Cl⁻/Br⁻/I⁻ halides | Soluble except AgX, PbX₂ (PbCl₂ slightly) |
| SO₄²⁻ sulfate | Soluble except BaSO₄, PbSO₄; CaSO₄, Ag₂SO₄ slightly |
| CO₃²⁻, PO₄³⁻ | Insoluble except K⁺/Na⁺/NH₄⁺ |
| OH⁻ hydroxide | Insoluble except K/Na/Ba; Ca(OH)₂ slightly |
Uses
They tell you whether a double-displacement reaction happens: it proceeds when a precipitate, gas or water forms (e.g. NaCl + AgNO₃ → AgCl↓ + NaNO₃).
Not sure? Use the interactive solubility table — click cation × anion for the product and whether it's soluble/slightly/insoluble.