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Single Displacement
&
Double Displacement
Single Displacement
Single Displacement Reactions
Single Displacement Reactions
Single displacement reaction – a reaction in
which an element displaces another element in
a compound, producing a new compound and a
new element.
General pattern:
A +
BC  AC
+
B
A + B C  A C + B
Ex: 2Mg (s) + CO2 (g)  2MgO (s) + C (s)
Single Displacement Reactions
Cu (s) + 2 AgNO3 (aq) 
Cu(NO3)2 (aq) + 2 Ag (s)
This rxn extract the silver from the silver nitrate solution.
reaction
This reaction often occurs in aqueous solution.
Example:
copper + silver nitrate  copper(II) nitrate + silver
Cu (s) + 2 AgNO3 (aq) 
Before
1 Cu atom
2
1 Ag+ ion
1 NO32- ion
2
Cu(NO3)2 (aq) + 2 Ag (s)
After
1 Cu2+ ion
2
1 Ag atom
2 NO32- ion
Single Displacement Reactions
Single displacement also occurs in when metals
are placed in acids (example HCl). The metal
atom will replace the hydrogen atom.
Example:
zinc + hydrochloric acid  hydrogen + zinc chloride
Zn (s) + 2 HCl (aq) 
H2 (g) +
ZnCl2 (aq)
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Single Displacement Reactions
Zn (s) +
2 HCl (aq) 
H2 (g) +
ZnCl2 (aq)
Single Displacement Reactions
Single displacement also occurs during metal
processing.
Metals are usually found combined with other
elements to form rock deposits (metal ores).
Example: Nickel is usually found as Nickel sulfide.
After smelting process it becomes Nickel oxide. It
is then burned with coke (carbon) to produce pure
nickel and carbon monoxide.
C(s) + NiO (s)  Ni (s) + CO (g)
Besides CO, the smelting process gives off SO2, a
contributor for acid rain.
Double Displacement Reactions
Double displacement reaction – a reaction that
occurs when elements in different compounds
displace each other or exchange places,
producing two new compounds.
General pattern:
AB
+ CD 
+
A B C D 
Double Displacement
AD
AD
+
+
CB
C B
reaction
Many double displacements occur between two
ionic compounds.
Double Displacement Reactions
Double Displacement Reactions
AB +
CD

AD
+
CB
Silver nitrate + sodium chloride  silver chloride + sodium nitrate
AgNO3 (aq)+ NaCl (aq)  AgCl (s) + NaNO3 (aq)
Precipitate formation from:
Silver nitrate + sodium chloride  silver chloride + sodium nitrate
AgNO3 (aq)+ NaCl (aq)  AgCl (s) + NaNO3 (aq)
One of the products above is a solid (AgCl) – this is
called a precipitate.
Many (but not all) double displacements produce
precipitate.
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Seatwork – complete the following:
• Worksheet “Single & Double Displacement”
HW:
Read 6.9
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