Chemical Reaction Types
There are 3 important general types of reactions:
1. Combination Reactions
Two or more different substances combine to form one substance:
A + B AB
2. Decomposition Reactions
One substance is broken down into smaller substances. Sometimes this is caused by heat (thermal
decomposition) or it can occur naturally. This is the opposite of combination reactions.
AB A + B
3. Displacement Reactions
One substance replaces another substance that is already bonded by taking its place. There are two
types, single and double displacement.
Single: A + BC AC + B
Double: AB + CD AD + BC
Fill in the table below to identify examples of reaction types. The first one has been done for you.
Reaction General Type
C + O2 CO2 Combination
NaCl + AgNO3 NaNO3 + AgCl
CaO + H2O Ca(OH)2
H2O2 H2 + O2
Fe + CuSO4 FeSO4 + Cu
CaCO3 + heat CaO + CO2
Specific Reaction Types
There are many of these, but some important ones are below.
Combustion (aka Burning)
This is the combination of a substance (fuel) with oxygen gas (O2)
CH4 + O2 CO2 + H2O
Methane + oxygen carbon dioxide + water
Mg + O2 MgO
Magnesium + oxygen magnesium oxide
Precipitation
When a solid (precipitate) is formed, often from a displacement reaction
PbNO3(aq) + KI(aq) KNO3(aq) + PbI2(s)
Lead nitrate + potassium iodide potassium nitrate + lead iodide (solid)
In the above reaction, lead iodide is insoluble
in water so it precipitates as a solid
States of matter
(aq) means “aqueous” indicating that the
substance is dissolved in water
(s) solid (l) liquid (g) gas
Fill in the table below:
Reaction Specific Reaction Type States of products
C(s) + O2(g) CO2(g)
NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s)
H2(g) + O2(g) H2O(l)