Types of chemical reactions
single-displacement reaction -- an element reacts with a compound
to replace one of the elements in the compound
• the products are a different element and a different compound
General form:
Single-displacement reactions
A common reaction is the displacement of hydrogen from water or an acid
In this case, hydrogen behaves like a metal
Examples:
If A and B are metals:
2 Na (s) + 2 H2O (l)
A + BC
B + AC
H2 (g) + 2 NaOH (aq)
( H–O–H )
Example:
Cu (s) + 2 AgNO3(aq)
2 Ag (s) + Cu(NO3 )2 (aq)
Types of chemical reactions
single-displacement reaction -- an element reacts with a compound to
replace one of the elements in the compound
• the products are a different element and a different compound
Zn (s) + 2 HCl (aq)
H2 (g) + ZnCl2 (aq)
Chemical activity series
Let’s start with an analogy…
Suppose there are two dogs but only one bone. Which dog gets the
bone?
General form:
If A and C are halogens:
A + BC
C + BA
Example:
Cl2 (g) + 2 NaBr (aq)
Br2 (l) + 2 NaCl (aq)
A: The dog that is more aggressive
Chemical activity series
If a more-aggressive dog encounters a less-aggressive dog with a bone,
the more-aggressive dog will displace the less-aggressive dog
Chemical activity series
Atoms in single-displacement reactions behave in a similar way, except
we substitute the word “active” for “aggressive”
In this case, chemistry obeys the Law of the Jungle
+
+
If a less-aggressive dog encounters a more-aggressive dog with a
bone…. Nothing happens ( no displacement occurs )
Example: Iron is more active than copper, so the following singledisplacement reaction will proceed
Fe (s) + CuSO4 (aq)
Cu (s) + FeSO4 (aq)
Example: Copper is less active than iron, so the following singledisplacement reaction will not proceed
+
+
increasing activity
Chemical activity series
Metals
K
Ca
Na
Mg
Al
Zn
Fe
Ni
Sn
Pb
H
Cu
Ag
Hg
Au
Halogens
F
Cl
Br
I
In general:
Atoms of an element in the
series will displace atoms of
those elements below it
Cu (s) + FeSO4 (aq)
Sample problems
Na (s) + AgNO3 (aq)
Cu (s) + FeCl3 (aq)
Mg (s) + 2 HBr (aq)
Remember:
Metals only displace other
metals
Halogens only displace other
halogens
no reaction
Cl2 (s) + 2 HI (aq)