Classifying Reactions
Types of Reactions
Consider these reactions:
CaCO3 (aq)  CaO (aq) + CO2 (g)
CO2 (g) + NaOH (aq)  NaHCO3 (aq)
a. How are these two reactions different?
b. How would you describe, in words, what
happens to the reactants in each case?
Types of Reactions
There are 6 categories of reactions:
1.
2.
3.
4.
5.
6.
Synthesis (Combination)
Decomposition
Single Exchange
Double Exchange
Combustion
Neutralization
What is Synthesis
(Combination)?
Two elements are combined.
A + B  AB
Example:
H2 + I2  2 HI
2Fe + 3Cl2  2FeCl3
2SO2 + O2  2 SO3
What is Decomposition?
A compound disintegrates or breaks down
into more than one compound.
AB  A + B
Example:
2H2O  2H2 + O2
Practice
Classify the following reactions. Explain your
reasoning.
CaO + H2O  Ca(OH)2
Combination
2Ag2O  4Ag + O2
Decomposition
C12H22O11  12C + 11H2O
Decomposition
2H2 + O2  2H2O
Combination
What is Single Exchange?
One atom/ion trades places with another.
A + BC  AC + B
Example:
Zn + H2SO4  ZnSO4 + H2
Cl2 + 2KBr  2KCl + Br2
What is Double Exchange?
Two atom/ions swap positions.
AB + CD  AD + BC
Example:
AgNO3 + NaCl  AgCl + NaNO3
HCl + NaOH  NaCl + H2O
What is Combustion?
A + oxygen  B + C
A is usually mainly composed of C and H.
B and C usually include H2O or CO2.
Example:
CH4 + 4O2  CO2 + 2H2O
C6H12O6 + 6O2  6CO2 + 6H2O
Practice
Classify the following reactions. Explain your
reasoning.
3Na + FePO4  Fe + Na3PO4
Single Exchange
ZnBr2 + 2AgNO3  Zn(NO3)2 + 2AgBr
Double Exchange
C3H8 + 5O2  4H2O + 3CO2
Combustion
Pb(NO3)2 + K2CrO4  KNO3 + PbCrO4
Double Exchange