2. Some Terminology Soluble – Will dissolve in a solvent Insoluble – Will not dissolve in a solvent Solvent – The substance that dissolves the solute Solute – The substance that dissolves in the solvent Solution – Produced when a solute dissolves in a solvent

3. Soluble and Insoluble Substances Water is often regarded as the universal solvent – meaning that it will dissolve any substance. This is not true. Substances can be divided into 3 categories, based on their solubility in water. – Substances that are soluble – Substances that are sparingly soluble – Substances that are insoluble

4. Solubility Rules Nitrates are all soluble. Chlorides are all soluble, except silver chloride and lead chloride. Sulfates are all soluble, except for lead sulfate, calcium sulfate and barium sulfate. Carbonates are all insoluble except those in grp 1 (sodium carbonate and potassium carbonate) and ammonium carbonate.

5. Solubility Rules Hydroxides are all insoluble, except those in grp 1 (sodium hydroxide, potassium hydroxide) and ammonium hydroxide.

6. Precipitates A precipitate (ppt) is an insoluble substance that forms when 2 soluble substances in solutions are mixed. A precipitation reaction is one in which a ppt is formed.

7. Example Copper Nitrate Sodium Hydroxide Copper Hydroxide Sodium Nitrate PPT Cu(NO 3 ) 2 2NaOHCu(OH) 2 2NaNO 3

8. Spectator Ions Every ionic compound in solution contains 2 independent ions. In all precipitation reactions, there are 2 spectator ions. These are ions that need to be present in a reaction but do not take part in the reaction.

9. Spectator Ions Example Cu(NO 3 ) 2(aq) 2NaOH (aq) Cu(OH) 2 (s) 2NaNO 3(aq) The symbol equation for the formation of the precipitate copper hydroxide is: With the spectator ions removed: Cu 2+ (aq) 2OH - (aq) Cu(OH) 2 (s)