1. Solubility Rules and Precipitation Reactions

2. Factors Affecting Solubility

3. Surface Area
More solute/solvent contact
means faster dissolving
Crush substance into fine
powder
Use mortar and pestle

4. Stirring or Agitation:
More solute/solvent
contact (solids/liquids)
However, stirring disturbs
dissolved gases and they
come out of solution.

5. Temperature of Solvent
Higher temperatures will allow more
solid solutes to dissolve

6. Gases dissolve better when solvent temperature is colder.
Ex: CO2 gas in hot soda (flat) vs. cold soda (fizzy)

7. Pressure
Effects gas solubility only
Why?
Increasing pressure on
a gas above a liquid
causes more gas
molecules to be
“pushed” into solution.
Ex: CO2(aq) in soda

8. Nature of Solute and Solvent
Polar solutes dissolve in polar solvents
Nonpolar solutes dissolve in nonpolar solvents
Most ionics (but not all) dissolve in polar solvents (molecule-ion attractions)

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

10. Solubility Rules All nitrates (NO3-) are soluble.
All ammonium (NH4+) or alkali (Li+, Na+, K+, Rb+, Cs+, Fr+) compounds are soluble.
All carbonates (CO32-), phosphates (PO4 3 -) and hydroxides (OH-) are insoluble except with the cations in Rule #2.
4. All chlorides (Cl-), bromides (Br-), and iodides (I-), are soluble except with Ag+, Pb2+, or Hg+.
5. All sulfates (SO42-) are soluble except with Ca2+, Sr2+, Ba2+, Ra2+, Pb2+,

11. Which of the following are soluble in water?
SrSO4
b. NaNO3
c. PbCl2
Not soluble
soluble
Not soluble

12. 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.

13. Precipitates
Precipitates are insoluble ionic compounds formed in double replacement reactions.
Determine which product is the insoluble precipitate by using your rules.

14. When a precipitate forms, you create a heterogeneous mixture.
You can separate a precipitate by filtration.
The solid will stay on the paper.

15. 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.

16. 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