1. Solubility Rules and Precipitation Reactions

2. Not all ionic compounds dissolve
Not all ionic compounds dissolve! Instead of doing experiments all the time to see which ones will dissolve, we use The solubility rules.

3. Compounds Containing the Following Ions
Solubility Rules
Rule
Compounds Containing the Following Ions
Solubility
Exceptions 1
Li+, Na+, K+, and NH4+
Soluble
None 2
NO3- and C2H3O2- 3
Cl-, Br-, and I-
When these ions pair with Ag+, Hg22+, or Pb2+, the compounds are insoluble 4
SO42-
When SO42- pairs with Sr2+, Ba2+, Pb2+, Ag+, or Ca2+, the compounds are insoluble 5
OH-
Insoluble
When these ions pair with Li+, Na+, K+, and NH4+, the compounds are soluble 6
CO32- and PO43-

4. Which of the following are soluble in water? SrSO4 NaNO3 PbCl2
Not soluble
soluble
Not soluble

5. Precipitation Reactions
When a solid doesn’t dissolve it is called insoluble. A solid that forms when two solutions are mixed is called a precipitate.

6. Predict the products of the following reaction: (if no solid precipitate is formed, there is no reaction)
Pb(NO3)2(aq) + KI (aq)  Pb(NO3)2(aq) + 2KI (aq)  PbI2(s) + 2KNO3 (aq)
We know it is a solid
precipitate because it is
insoluble according to
the solubility rules.

7. Net Ionic Equation
Write the balanced chemical and net ionic equation for: Na2CO3(aq) + CaCl2(aq)  Step 1: Write the balanced chemical equation Na2CO3(aq) + CaCl2(aq)  CaCO3(s) + 2NaCl (aq) Step 2: Remove the spectator ions (those that are soluble). Ca2+(aq) + CO32-(aq)  CaCO3(s)
Insoluble precipitate