- Solubility rules are qualitative rules to determine whether an ionic compound will, or will not, dissolve in water at 25°C. 1
- An ionic compound that does dissolve in water is said to be soluble.2
The result is an aqueous solution.
Aqueous solution of a salt is indicated by placing the letters aq in round brackets, (aq), to the right of the formula for the ionic compound.
- An ionic substance that does not dissolve in water is said to be insoluble.3
The result is a precipitate, an insoluble solid.
Precipitate of a salt is indicated by placing the letter s in round brackets, (s), to the right of the formula for the ionic compound.
- Solubility Rules can be given as a list, a table, or a chart.
- Solubility Rules can be used to decide if a precipitate (an insoluble substance) will form from an aqueous solution at 25°C:
- List the anions and cations in the solution
- List the possible ionic compounds that could be produced
- Use the solubility rules (list, table or chart) to decide if either of the ionic compounds are insoluble and will therefore form a precipitate.