1. Precipitation Reactions
& Solubility Rules

2. Precipitation Reactions
Precipitation Rxn: A reaction that produces an insoluble product, a.k.a… a precipitate
Insoluble: Does NOT dissolve in water (not aqueous!) these substances are labeled (s) for solid
Important to remember:
(s) = SOLID = NOT SOLUBLE IN WATER!!!
(aq) = AQUEOUS = SOLUBLE IN WATER!!!

3. Find the Precipitate… AgNO3(aq) + KCl(aq)  AgCl(s) + KNO3(aq)
Silver Chloride is a solid, (s).
It does NOT dissolve in water—it’s a PRECIPITATE!
Review From Yesterday: Can you write total and net ionic equations for this reaction?

4. Precipitation of Silver Chloride
Molecular Equation:
AgNO3(aq) KCl(aq)  AgCl(s) KNO3(aq)
Total Ionic Equation:
Ag+(aq) + NO3-(aq) + K+(aq) + Cl-(aq)  AgCl(s) + K+(aq) + NO3-(aq)
Net Ionic Equation:
Ag+(aq) + Cl-(aq)  AgCl(s)
Spectator Ions:
NO3- & K+

5. Precipitation of Silver Chloride
Precipitate: AgCl Spectator Ions: NO3- & K+ K+ K+
NO3‾
Ag+
Cl‾
NO3‾
AgCl

6. Predicting Precipitation Reactions
How do we know whether a certain compound is aqueous or solid?
(How do we know whether it is SOLUBLE or not?)
We need SOLUBILITY RULES in order to:
Determine if a precipitate is formed in a reaction
Write correct Total and Net Ionic equations

7. Solubility Rules (Describe solubility of substances in WATER)
Notice the ions that are soluble NO MATTER WHAT they form compounds with! These ions will ALWAYS be SPECTATOR IONS!!!

8. Predicting Precipitation Reactions
Will a precipitate (s) form when solutions of Calcium Chloride and Sodium Carbonate are mixed?
This is a double replacement reaction (don’t forget to balance!)
CaCl2(?) + Na2CO3(?)  CaCO3(?) + 2NaCl(?)

9. Predicting Precipitation Reactions
Will a precipitate (s) form when solutions of Calcium Chloride and Sodium Carbonate are mixed?
CaCl2(aq) + Na2CO3(aq)  CaCO3(s) + 2NaCl(aq)
Yes! ppt = CaCO3
(Calcium Carbonate = chalk!)

10. Total Ionic and Net Ionic Equations
Now that we have labeled each substance using the SOLUBILITY RULES, we should be able to write
Total Ionic and Net Ionic Equations
CaCl2(aq) + Na2CO3(aq)  CaCO3(s) + 2NaCl(aq)
Total Ionic:
Ca+2(aq) + 2Cl- (aq) + 2Na+(aq) + CO3-2(aq)  CaCO3(s) + 2Na+(aq) + 2Cl-(aq)
Net Ionic:
Ca+2(aq) + CO3-2(aq)  CaCO3(s)
Cl‾
Na+
Ca+2
Na+
CO3‾2
Cl‾
CaCO3