1. Ch. 11.3: Chemical Reactions
Writing Net Ionic Equations &
Solubility Rules
Honors Chemistry

2. Precipitation Reactions
Remember that all ionic compounds are considered strong electrolytes
dissociate completely in water
When two solutions are mixed, free ions are floating around
They collide together randomly
If an ionic compound forms that is insoluble in water, it is called a precipitation reaction

3. Precipitation Reactions
If no insoluble compound forms, no reaction has actually happened
It is just a solution with lots of free ions floating around
Spectator Ions
free ions not involved in chemical reaction

4. Precipitation Reactions

5. Solubility Rules
Rules that help us predict which compounds will be soluble/insoluble

6. Solubility Rules All group IA salts are soluble.
All ammonium salts are soluble.
All salts containing nitrate, acetate, chlorate, and perchlorate are soluble.
All salts are containing halides are soluble EXCEPT silver, mercury(I), and lead.
All sulfate salts are soluble EXCEPT barium, calcium, strontium, silver, mercury(I), and lead.
All salts containing carbonates, phosphates, and chromates are insoluble EXCEPT for rules #1 and #2.
All sulfide salts are insoluble EXCEPT for rules #1 and #2 and calcium, strontium, and barium.
All hydroxide salts are insoluble EXCEPT rules #1 and #2 and barium and strontium.
** Will be given for a test or quiz, no need to memorize!!

7. Is it Soluble? Na3PO4 Yes- (aq) PbCl2 No- (s) AgNO3 (NH4)2SO4 BaCO3
Fe(CH3COO)3
Yes- (aq)
CaSiO3
Ni(OH)2

8. Types of Reactions molecular equation complete ionic equation
overall reaction
normal type we have been writing
complete ionic equation
all strong electrolytes are broken into ions
net ionic equation
all spectator ions are cancelled out
only includes species active in chemical reaction

9. Types of Electrolytes Break Apart (Strong)
must be (aq)
soluble ionic compounds
Don’t break apart (weak/non)
anything (g), (s), (l)

10. Tips for writing equations
Balance at the beginning
should stay balanced the whole way through
may simplify at the end if necessary
All ions should be (aq) – break apart for ionic equation
Keep symbols (i.e.- aq, s, l, g) written through entire process
Cancel out spectator ions and common ions on both sides for net ionic equation

11. Write the net ionic equations
solution of strontium chloride is mixed with solution of potassium sulfate
SrCl2(aq) + K2SO4(aq)  SrSO4(s) + 2KCl(aq)
complete ionic:
Sr2+(aq) + 2Cl-(aq) +2K+(aq) + SO42-(aq)  SrSO4(s) + 2K+(aq) + 2Cl-(aq)
spectators: 2Cl-(aq) and 2K+(aq)
net ionic:
Sr2+(aq) + SO42-(aq)  SrSO4(s)

12. Write the net ionic equations
solution of sodium sulfide and solution of iron (II) nitrate are mixed
Na2S(aq) + Fe(NO3)2(aq)  2NaNO3(aq) + FeS(s)
complete ionic:
2Na+(aq) + S2-(aq) + Fe2+(aq) + 2NO3-(aq)  2Na+(aq) + 2NO3-(aq) + FeS(s)
spectators: 2Na+(aq) and 2NO3-(aq)
net ionic:
S2-(aq) + Fe2+(aq)  FeS(s)

13. Write the net ionic equations
Solution of aluminum chloride and solution of silver nitrate are mixed
AlCl3(aq) + 3AgNO3(aq)  3AgCl(s) + Al(NO3)3(aq)
complete ionic:
Al3+(aq) + 3Cl-(aq) + 3Ag+(aq) + 3NO3-(aq)  3AgCl(s) + Al3+(aq) + 3NO3-(aq)
spectators: Al3+(aq) and 3NO3-(aq)
net ionic:
3Cl-(aq) + 3Ag+(aq)  3AgCl(s)
Cl-(aq) + Ag+(aq)  AgCl(s)

14. In Conclusion
Remember net ionic equations identify what is ACTIVE in a chemical reaction
There are three steps that need to be identified to be able to write a complete net ionic equation
Make sure you understand each step!
Homework: 11.3 Practice Problems