Types of Chemical Reactions
Anatomy of a chemical equation
2H2(g)
+
O2(g) 
2H2O(l)
The numbers that are placed in front of the chemical formulas are called __________. They refer to the
quantity of each atom or element present in the reaction.
The letters placed at the bottom of each chemical formula are called __________; they refer to the state
of the substance. ie: (g) =
, (l) =
, (s) =
, (aq) =
(a solution with water as the
solvent)
There are five types of Chemical Reactions:
Synthesis
Decomposition
Double Displacement
Synthesis Reactions
What does “synthesis” mean?
E+EC
or
C+ C C
E=element C= compound
a) Element + oxygen  oxide (this is also a combustion reaction)
b) Metal + nonmetal  binary compound (salt)
Ex.
Zn(s) + S(s) ---> ZnS(s)
Na(s) +
Cl2(g) ---->
NH3(g) + HCl(g) ----->
NaCl(s)
NH4Cl(s)
Decomposition Reactions
What does decomposition mean?
CE+E
or
C C+E
The types are the same as the synthesis reactions but reversed.
Let’s try some examples:
ex.
Energy + H2O (l) --->
H2 (g) +
ex.
Na3N(s)
ex.
CaCO3(s) ----> CO2(g) + CaO(s)
-----> Na(s) + N2(g)
O2(g)
Single Displacement Reactions
A + BC  AC + B
or
AB + C  AC + B
In these reactions, a metal element replaces metal in a compound, or non-metal element replaces nonmetal in a compound.
**Reminder  Cation: positive ion, Anion: negative ion
ex.
sodium + silver fluoride
------> silver
ex.
Cu +
CuCl2
ex.
F2
ex.
Zn + HCl
AgCl ---->
+ NaCl ------>
----->
NaF
+
+ sodium fluoride
Ag
+ Cl2
ZnCl2 + H2
Double Displacement Reactions
A D.D reaction involves the exchange of __________ between two ionic compounds, usually in aqueous
solution. They are double swap reactions, the two reactants trade places! There are three different
forms of the D.D. reactions, we will talk about two:
1) Some ionic substances when mixed do not dissolve in water and a __________ is formed ( a solid
that forms as a result of a chemical reaction). This reaction called a ____________ reaction
Precipitate!
ex.
AgNO3(aq) + NaCl(aq) ----->
ex.
KI(aq) +
AgCl (s)
Pb(NO3)2(aq) ---->
+ NaNO3(aq)
KNO3(aq)
+
PbI2(s)
2) Salt and water is formed. This is called a neutralization reaction. In this reaction an acid and a base
react to form neutral water and a salt (ionic compound)
ex.
HCl(aq) +
ex.
H2SO4(aq)
NaOH(aq) ----->
H2O(l)
+
+ KOH ----> K2SO4(aq)
NaCl(aq)
+ H20(l)
Combustion Reaction
A Rapid reaction of a substance with __________. This releases energy in the form of heat and light.
Mg + O2 ----> MgO + Energy (also synthesis)
Substances with carbon and hydrogen form carbon dioxide and water as products. This results when
oxygen is plentiful and is called complete combustion. (Blue Flame)
For example:
C3H8 (g) +
O2 (g) 
CO2 (g) +
H2O(g)
Incomplete combustion results in production of carbon monoxide (poisonous gas) and/or soot (solid
carbon), when oxygen is not plentiful. (Yellow Flame)
For example:
C4H10(g) +
O2(g) ------->
CO(g)
+ H2O(g) + energy