Chemistry
Types of Chemical Reactions
Types of Chemical Reactions

Many chemical
reactions have
defining
characteristics which
allow them to be
classified as a type.
Types of Chemical Reactions

OBJECTIVES:
Describe
the five general
types of reactions.
Predict
the products of the
five general types of reactions.
Types of Chemical Reactions

The five types of chemical reactions in this
unit are:
 Synthesis
 Decomposition
 Single Replacement
 Double Replacement
 Combustion
5 Types of Reactions Video
Synthesis Reactions


Two or more substances combine to form
one substance.
 The general form is A + X AX
Example:
 Magnesium + oxygen  magnesium
oxide
 2Mg + O2  2MgO
Synthesis Reactions


Synthesis reactions may also be called
composition or combination reactions.
Some types of synthesis reactions:

Combination of elements
 K + Cl2 
 One product will be formed
Synthesis Reactions

Write the equation

K + Cl2 

Balance the equation: 2K + Cl2  2KCl
KCl
Synthesis Reactions

Examples of synthesis reactions:
 SO2
+ H2O  H2SO3
 BaO
+ H2O  Ba(OH)2
 Na2O
 CaO
+ CO2  Na2CO3
+ SO2  CaSO3
Synthesis Reactions


Elements or compounds combine to
form ONE product
The only synthesis reactions you will
be asked to determine would be the
very simple ones with only 1 possible
answer A + B = AB

E.g. K + Cl2 = KCl
Decomposition Reactions


One substance reacts to form two or more
substances.
 The general form is AX  A + X
Example:
 Water can be decomposed by
electrolysis.
 2H2O  2H2 + O2
Decomposition Reactions

Examples of Decomposition Reactions:
 CaCO3
 CaO + CO2
 H2CO3  H2O + CO2
 Ca(OH)2  CaO + H2O
 2KClO3  2KCl + 3O2
 Zn(ClO3)2  ZnCl2 + 3O2
Decomposition Reactions

Some substances can easily
decompose:
Ammonium hydroxide is actually
ammonia gas dissolved in water.
 NH4OH  NH3 + H2O
 Some acids decompose into water and
an oxide.
 H2SO3  H2O + SO2

Decomposition Reactions

The only decomposition reactions you will
be asked to determine would be the
simple ones with only 1 possible answer

E.g. 2H2O  2H2 + O2
Types of Chemical Reactions
Single Replacement Reactions
Double Replacement Reactions
Combustion Reactions
Recall
Synthesis Reactions
 Two or more substances combine to form
one substance.
 The general form is A + X AX
Decomposition Reactions
 One substance reacts to form two or more
substances.
 The general form is AX  A + X
Single Replacement Reactions

A metal will replace a metal ion in a
compound.


The general form is A + BX  AX + B
A nonmetal will replace a nonmetal
ion in a compound.

The general form is Y + BX  BY + X
Single Replacement Reactions

Examples:
 Ni + AgNO3 
 Nickel replaces the metallic ion Ag+ (metal
replaces metal ion)
 The silver becomes free silver and the
nickel becomes the nickel (II) ion.
 Ni + AgNO3  Ag + Ni(NO3)2
 Balance the equation:
 Ni + 2AgNO3  2Ag + Ni(NO3)2
Thermite Reaction
Thermite Video
Thermite Reaction
Al + Fe2O3 
 Aluminum will replace iron (III) as
was seen in the video.
 Iron (III) becomes Fe and aluminum
metal becomes Al3+.
 2Al + Fe2O3  2Fe + Al2O3

Double Replacement Reactions


Ions of two compounds exchange
places with each other.
Reactants must be two ionic
compounds, in aqueous solution
 The
general form is AX + BY 
AY + BX
Double Replacement






NaOH + CuSO4 
The Na+ and Cu2+ switch places.
Na+ combines with SO42- to form Na2SO4.
Cu2+ combines with OH- to form Cu(OH)2
NaOH + CuSO4  Na2SO4 + Cu(OH)2
2NaOH + CuSO4  Na2SO4 + Cu(OH)2
Double Replacement
CuSO4 + Na2CO3 
 Cu2+ combines with CO32- to form
CuCO3.
 Na+ combines with SO42- to form
Na2SO4.
 CuSO4 + Na2CO3  CuCO3 + Na2SO4

Double Replacement Reactions
•
•
•
Think about it like “foil”ing in algebra, first and
last ions go together + inside ions go together
Example:
AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq)
Another example:
K2SO4(aq) + Ba(NO3)2(aq)  2 KNO3(aq) + BaSO4(s)
Recognition

You need to be able to recognize which
reaction is taking place
Practice Examples:
H2 + O2 
 H2O 
 Zn + H2SO4 
 HgO 
 KBr + Cl2 


AgNO3 + NaCl 

Mg(OH)2 + H2SO3 
Synthesis
 Decomposition


Single Replacement

Decomposition

Single Replacement

Double Replacement

Double Replacement
Classifying Chemical Reactions Flintstones Video
Combustion Reactions




Combustion means “add oxygen”
Normally, a compound composed of only C,
H, (and maybe O) is reacted with oxygen –
usually called “burning”
If the combustion is complete, the
products will be CO2 and H2O.
If the combustion is incomplete, the
products will be CO (or possibly just C) and
H2O.
Combustion Reaction
When a substance combines with
oxygen, a combustion reaction can
result.
 The combustion reaction may also be
an example of an earlier type such as
2Mg + O2  2MgO.
 An example of a combustion reaction
is burning of fuel like gas or oil.

Combustion Reactions
Combustion reactions involve light
and heat energy released.
 Natural gas, propane, gasoline, etc.
are burned to produce heat energy.
 Most of these organic reactions
produce water and carbon
dioxide.

Combustion Reaction

When hydrocarbon compounds CxHx
are burned in oxygen, the products
are water and carbon dioxide.
CH4 + O2  CO2 + H2O
 CH4 + 2O2  CO2 + 2H2O

Combustion Reactions


Generally combustion reactions involve the
burning of a Hydrocarbon (CxHx) in
Oxygen.
Other elements can also burn with Oxygen



2Mg + O2  2MgO + Energy
2H2 + O2  2H2O + Energy (basis behind
fuel cell energy)
P4 + 5O2  P4O10 + Energy (matches)
So you want to make a product video
Practice


Classify each of the following as to
type:
H2 + Cl2  2HCl


Synthesis
Ca + 2H2O  Ca(OH)2 + H2

Single replacement
Practice

2CO + O2  2CO2


Synthesis and combustion
2KClO3  2KCl + 3O2

Decomposition
Practice

FeS + 2HCl  FeCl2 + H2S


Double replacement
Zn + HCl  ?
Single replacement
 Zn + 2HCl  ZnCl2 + H2

End of Day 2

Types of Chemical Reactions Worksheet