Double Displacement
• 2 compounds are reacted together
and the first part of each compound
will switch places
• general equation :
WX + YZ  WZ + YX
There are three types of double
displacement reactions:
• a reaction that forms a solid
• a reaction that forms a gas
• a reaction that forms water
(neutralization)
A reaction that forms a solid:
• A common observation during a double
displacement reaction is the formation of a
solid precipitate
• ex. Pb(NO3)2 (aq) + 2KI (aq)  PbI2 (s) + 2KNO3 (aq)
Solubility Table
•
You have been given a solubility table on the back of your
periodic table
• To use your solubility table:
– Identify the anion in the top row
– Identify the cation in the column below the
chosen anion
– If they have a high solubility then a precipitate
will not be formed, if they have a low solubility
then a precipitate likely will form.
A reaction that forms a gas:
• Sometimes a double displacement produces a gas
rather than a precipitate.
Reactants
Products
Acid + compound containing
carbonate ion
Ionic compound + water +
carbon dioxide
Compound containing
ammonium ions + compound
containing hydroxide ions
Ionic compound + water +
ammonia
A reaction that forms water:
• When a reaction takes place through the
combination of an acid and a base which results in
the formation of water is called Neutralization
• Neutralization: the process of making
a solution neutral (pH = 7) by adding
a base to an acidic solution or by
adding an acid to a basic solution
Summary of Double Displacement
If one reactant :
If the other reactant:
Then the products will
include:
Is an Aqueous Salt
Is an Aqueous Salt
A Precipitate
Is an Acid
Has Carbonate Ions
Water and carbon Dioxide
Has Ammonium Ions
Has Hydroxide Ions
Water and Ammonia
Is an Acid
Has hydroxide Ions
Water + a Salt
Practice Problems
1) Potassium carbonate and hydrochloric acid
2) Ammonium chloride and sodium hydroxide
3) Calcium carbonate and acetic acid
4) Lithium hydroxide and ammonium bromide
5) Sulfuric acid and lithium hydroxide
6) Calcium hydroxide and nitric acid
Practice Problems
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1)Potassium carbonate and hydrochloric acid
K2CO3(aq) +2 HCl(aq)  2KCl (aq) + H2O(l) + CO2(g)
2) Ammonium chloride and sodium hydroxide
NH4Cl(aq) + NaOH (aq)  NaCl (aq) + NH3 (g) + H2O(l)
3) Calcium carbonate and acetic acid
CaCO3(s) + 2HCH3COO(aq)  Ca(CH3COO)2(aq) + H2O (l) + CO2 (g)
4) Lithium hydroxide and ammonium bromide
LiOH(aq) + NH4Br(aq)  LiBr(aq) + H2O (l) NH3(g)
5) Sulfuric acid and lithium hydroxide
H2SO4(aq) + 2LiOH(aq)  Li2SO4(aq) + 2H2O(l)
6) Calcium hydroxide and nitric acid
Ca(OH)2(aq) + 2HNO3(aq)  Ca(NO3)2 (aq) +2H2O(l)