1. Predicting the Products of Double Replacement Reactions
Using a Solubility Table

2. Introduction
Double replacement reactions are reactions that occur in solution.
Cations and anions change places in double replacement reactions.
One product must be:
solid (precipitate)
insoluble gas
water

3. Basics Double replacement reactions have the following form:
AX(aq) + BY(aq) → AY(s) + BX(aq)
For example:
BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)
Pb(NO3)2(aq) + 2 HCl(aq) → PbCl2(s) + 2 HNO3(aq)
KOH(aq) + HBr(aq) → H2O(l) + KBr(aq)

4. BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)
Basics
In each of these reactions, the cations and anions change partners:
BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)

5. BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)
Basics
In each of these reactions, the cations and anions change partners:
BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)

6. BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)
Basics
In each of these reactions, the cations and anions change partners:
BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)

7. Basics Again, one of the products must be:
a precipitate (indicated by (s) or ↓)
an insoluble gas (indicated by (g) or ↑)
water (from the reaction of an acid with a base)
We will be looking at those reactions which form (or don’t form) precipitates as products

8. Solubility
Solubility is the ability of a compound, called the solute, to dissolve in a liquid, called the solvent.
Different compounds have different solubilities.
We are interested in those compounds that are not very soluble.
We want to know which ones form precipitates.

9. Solubility
We have a set of guidelines for the solubility of ionic compounds in water.
The guidelines tell us whether or not a particular family of ionic compounds is soluble.
We can use these guidelines to predict the formation of a participate in a potential double replacement reaction.
If no precipitate forms, then there is no reaction.

10. Solubility Guidelines
Most sodium, Na+, potassium, K+, and ammonium, NH4+, compounds are soluble in water.
Most nitrate, NO3−, acetate, CH3COO−, and chlorate, ClO3−, compounds are soluble in water.
Most chloride, Cl−, compounds are soluble, except those of silver, AgCl, mercury(I), Hg2Cl2, and lead, PbCl2. Lead(II) chloride is soluble in hot water.
Most sulfate, SO42−, compounds are soluble, except those of barium, BaSO4, strontium, SrSO4, and lead, PbSO4.
Most carbonate, CO32−, phosphate, PO43−, and silicate, SiO32−, compounds are insoluble, except those of sodium, potassium, and ammonium.
Most sulfides, S2−, compounds are insoluble, except those of calcium, Ca2+, strontium, Sr2+, sodium, Na+, potassium, K+, and ammonium, NH4+.

11. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
Pb(NO3)2
PbSO4
Na2SO4
Na2SO4
NaNO3
These are already in solution.
We know that two of the possible precipitates are soluble.

12. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
Next, we look at the solubility guidelines
PbSO4
Na2SO4
Most Na+, K+, and NH4+ compounds are soluble in water.
NaNO3
NaNO3

13. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
Next, we look at the solubility guidelines
PbSO4
Na2SO4
Most NO3–, CH3COO–, and ClO3– compounds are soluble in water.
NaNO3

14. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
Next, we look at the solubility guidelines
PbSO4
Na2SO4
Most Cl– compounds are soluble, except those of Ag+, Hg22+, and Pb2+.
NaNO3

15. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
Next, we look at the solubility guidelines
PbSO4
Na2SO4
Most SO42– compounds are soluble, except those of Ba2+, Sr2+, and Pb2+.
NaNO3

16. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
Next, we look at the solubility guidelines
PbSO4
Na2SO4
PbSO4 will be a precipitate.
NaNO3

17. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
We now complete the equation.
PbSO4
Na2SO4
PbSO4 will be a precipitate.
NaNO3

18. Applications
Example 1. Predict the result of mixing a solution of lead(II) nitrate with sodium sulfate. Pb(NO3)2(aq) + Na2SO4(aq) → PbSO4(s) + 2 NaNO3(aq) Cations Anions Possible precipitates Pb2+ NO3– Na+ SO42–
Pb(NO3)2
We now complete the equation.
PbSO4
Na2SO4
PbSO4 will be a precipitate.
NaNO3

19. Applications
Example 2. Predict the result of mixing a solution of copper(II) nitrate with sodium chloride. Cu(NO3)2(aq) + NaCl (aq) Cations Anions Possible precipitates Cu2+ NO3– Na+ Cl–
Cu(NO3)2
Cu(NO3)2
CuCl2
NaCl
NaCl
NaNO3
These are already in solution.
We know that two of the possible precipitates are soluble.

20. Applications
Example 2. Predict the result of mixing a solution of copper(II) nitrate with sodium chloride. Cu(NO3)2(aq) + NaCl (aq) Cations Anions Possible precipitates Cu2+ NO3– Na+ Cl–
Cu(NO3)2
Cu(NO3)2
Next, we look at the solubility guidelines
CuCl2
NaCl
NaCl
Most Na+, K+, and NH4+ compounds are soluble in water.
NaNO3
NaNO3

21. Applications
Example 2. Predict the result of mixing a solution of copper(II) nitrate with sodium chloride. Cu(NO3)2(aq) + NaCl (aq) Cations Anions Possible precipitates Cu2+ NO3– Na+ Cl–
Cu(NO3)2
Cu(NO3)2
Next, we look at the solubility guidelines
CuCl2
NaCl
NaCl
Most NO3–, CH3COO–, and ClO3– compounds are soluble in water.
NaNO3

22. Applications
Example 2. Predict the result of mixing a solution of copper(II) nitrate with sodium chloride. Cu(NO3)2(aq) + NaCl (aq) Cations Anions Possible precipitates Cu2+ NO3– Na+ Cl–
Cu(NO3)2
Cu(NO3)2
Next, we look at the solubility guidelines
CuCl2
CuCl2
NaCl
NaCl
Most Cl– compounds are soluble, except those of Ag+, Hg22+, and Pb2+.
NaNO3

23. Applications
Example 2. Predict the result of mixing a solution of copper(II) nitrate with sodium chloride. Cu(NO3)2(aq) + NaCl (aq) Cations Anions Possible precipitates Cu2+ NO3– Na+ Cl–
Cu(NO3)2
Cu(NO3)2
Next, we look at the solubility guidelines
CuCl2
CuCl2
NaCl
NaCl
There is no precipitate and no reaction.
NaNO3

24. Applications
Example 2. Predict the result of mixing a solution of copper(II) nitrate with sodium chloride. Cu(NO3)2(aq) + NaCl (aq) Cations Anions Possible precipitates Cu2+ NO3– Na+ Cl–
Cu(NO3)2
Cu(NO3)2
We now complete the equation.
CuCl2
CuCl2
NaCl
NaCl
There is no precipitate and no reaction.
NaNO3

25. Applications
Example 2. Predict the result of mixing a solution of copper(II) nitrate with sodium chloride. Cu(NO3)2(aq) + NaCl (aq) → no reaction Cations Anions Possible precipitates Cu2+ NO3– Na+ Cl–
Cu(NO3)2
Cu(NO3)2
We now complete the equation.
CuCl2
CuCl2
NaCl
NaCl
There is no precipitate and no reaction.
NaNO3

26. Practice Problems
Predict the result of mixing each of the following solutions.
AgNO3(aq) + NaCl(aq) →
Cu2SO4(aq) + Na2CO3(aq) →
BaCl2(aq) + CuSO4(aq) →
Pb(CH3COO)2(aq) + Na3ClO3(aq) →
FeCl2(aq) + CaS(aq) →
AgCl(s) + NaNO3(aq)
CuCO3(s) + Na2SO4(aq)
BaSO4(s) + CuCl2(aq)
no reaction
FeS(s) + CaCl2(aq)