CLASSIFYING
CHEMICAL REACTIONS
FIVE BASIC WAYS TO CLASSIFY
CHEMICAL REACTIONS:
1.
2.
3.
4.
5.
Synthesis
Decomposition
Single-Replacement
Double-Replacement
Combustion
Synthesis Reactions:
• Generic Reaction
• X + Y-->XY
• Definition-In this
equation, X and Y
can be compounds
or elements. The
result XY is a
compound.
2 Reactants and 1 Product
Analogy- Like a marriage
Examples of Real
Synthesis Reactions:
•
•
•
•
•
•
2Ba + O2 -->2BaO
4Cu + O2 -->2Cu2O
2Cu + O2 -->2CuO
2H2 + O2 -->2H2O
C + O2 -->CO2
2Na + Cl2 -->2NaCl2
Synthesis of Iron and Sulfur
Decomposition Reactions:
• In a decomposition
reaction, an compound Analogy-Like divorce
is broken down into two
simpler substances.
The generic formula of
a decomposition
reaction is:
• XY --> X + Y
• Decomposition
reactions are the
opposite of synthesis
1 Reactant and 2 Products
reactions.
Examples of Real
Decomposition Reactions:
•
•
•
•
•
2HgO --> 2Hg + O2
2H2O --> 2H2 + O2
CaCO3 --> CaO + CO2
Cu(OH)2 --> CuO + H2O
2KClO3 --> 2KCl + 3O2
H2SO4 --> SO3 + H2O
Decomposition of Hydrogen
Peroxide
Single Replacement Reactions:
• In this type of
reaction, one
element replaces a
similar element in a
compound.
More reactive metal wins
• A + XY --> AY + X
• In this equation, A, 1 free element + compound 
compound + 1 free element
X, and Y are the
elements and XY,
Analogy: Like finding a
AY, and XA are the
new mate
compounds.
Examples of Single
Replacement Reactions:
•
•
•
•
•
2Al + 3Fe(NO3)2  3Fe + 2Al(NO3)3
Zn + CuCl2 
Mg + Pb(NO3)2 
Fe + Na3PO4 
2K + ZnCl2 
Examples of Real
Single Replacement Reactions:
•
•
•
•
•
•
2Al + 3Fe(NO3)2  3Fe + 2Al(NO3)3
Zn + CuCl2  Cu + ZnCl2
Mg + Pb(NO3)2  Pb + Mg (NO3)2
Fe + Na3PO4  N.R.
2K + ZnCl2  2 KCl + Zn
Cl2 + 2KBr  2KCl + Br2
Hydrochloric acid and Zinc
Double-Replacement Reactions:
• In a doubleAnalogy: Like swapping
replacement reaction,
partners
the two compounds
exchange places in a
solution to form two
new compounds. The
general equation of a 2 compounds  2 compounds
double-replacement
reaction is: AB + XY --> AY + XB
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(s)  AgCl(s) + NaNO3(aq)
• Another example:
K2SO4(aq) + Ba(NO3)2(aq)  2 KNO3(aq) + BaSO4(s)
Examples of Real
Double-Replacement Reactions:
• Pb(NO3)2 + 2KI --> PbI2 + 2KNO3
• FeS + 2HCl --> H2S + FeCl2
• HCl + NaOH --> NaCl + H2O
Potassium Iodide and Lead
(II) Nitrate
Combustion Reactions:
• When a
substance
combines with
oxygen releasing
a large amount of
energy in the
form of light and
heat, it is a
combustion
reaction.
Oxygen is needed to
Burn things.
Generic Equation:
C + O2  CO2 + heat
Examples of Real
Combustion Reactions:
• examples of combustion reactions
• C3H8 + 5O2 --> 3CO2 + 4H2O + heat
• 2CH4 + 4O2  2CO2 + 4H2O + heat
Gummy Bear Sacrifice
FIVE BASIC WAYS TO CLASSIFY
CHEMICAL REACTIONS:
•
•
•
•
•
Synthesis 2 reactants1 product (like marriage)
Decomposition 1 reactant 2 products(like divorce)
Single-Replacement (most reactive element wins)
Double-Replacement (switch partners)
Combustion=Burning (need oxygen to burn things)