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LecturePLUS Timberlake 99
Chapter 5Chemical Reactions and
Quantities
Types of Reactions
Oxidation-Reduction Reactions
LecturePLUS Timberlake 99
Type of Reactions
Chemical reactions are classified into four general types
Combination
Decomposition
Single Replacement
Double Replacement
LecturePLUS Timberlake 99
Combination (Synthesis)
Two or more elements or simple compounds combine to form (synthesize) one product
A + B AB
2Mg + O2 2MgO
2Na + Cl2 2NaCl
SO3 + H2O H2SO4
LecturePLUS Timberlake 99
Decomposition
One substance is broken down (split) into two or more simpler substances.
AB A + B
2HgO 2Hg + O2
2KClO3 2KCl + 3 O2
LecturePLUS Timberlake 99
Learning Check R1
Classify the following reactions as
1) combination or 2) decomposition:
___A. H2 + Br2 2HBr
___B. Al2(CO3)3 Al2O3 + 3CO2
___C. 4 Al + 3C Al4C3
LecturePLUS Timberlake 99
Solution R1
Classify the following reactions as
1) combination or 2) decomposition:
_1_A. H2 + Br2 2HBr
_2_B. Al2(CO3)3 Al2O3 + 3CO2
_1_C. 4 Al + 3C Al4C3
LecturePLUS Timberlake 99
Single Replacement
One element takes the place of an element in a reacting compound.
A + BC AB + C
Zn + 2HCl ZnCl2 + H2
Fe + CuSO4 FeSO4 + Cu
LecturePLUS Timberlake 99
Double Replacement
Two elements in reactants take the place of each other
AB + CD AD + CB
AgNO3 + NaCl AgCl + NaNO3
ZnS + 2HCl ZnCl2 + H2S
LecturePLUS Timberlake 99
Learning Check R2
Classify the following reactions as
1) single replacement
2) double replacement
__A. 2Al + 3H2SO4 Al2(SO4)3 + 3H2
__B. Na2SO4 + 2AgNO3 Ag2SO4 + 2NaNO3
__C. 3C + Fe2O3 2Fe + 3CO
LecturePLUS Timberlake 99
Solution R2
Classify the following reactions as
1) single replacement
2) double replacement
1_A. 2Al + 3H2SO4 Al2(SO4)3 + 3H2
2_B. Na2SO4 + 2AgNO3 Ag2SO4 + 2NaNO3
1_C. 3C + Fe2O3 2Fe + 3CO
LecturePLUS Timberlake 99
Combustion
A reaction in which a compound (often
carbon) reacts with oxygen
C + O2 CO2
CH4 + 2O2 CO2 + 2H2O
C3H8 + 5O2 3CO2 + 4H2O
C6H12O6 + 6O2 6CO2 + 6H2O
LecturePLUS Timberlake 99
Learning Check R3
Balance the combustion equation
___C5H12 + ___O2 ___CO2 + ___H2O
LecturePLUS Timberlake 99
Solution R3
Balance the combustion equation
1 C5H12 + 8 O2 5 CO2 + 6 H2O
LecturePLUS Timberlake 99
Oxidation and Reduction
Reactions that involve a loss or gain of electrons
Occurs in many of the 4 types of reactions and combustion
Important in food metabolism, batteries, rusting of metals
LecturePLUS Timberlake 99
Requirements for Oxidization-Reduction
Electrons are transferred
Two processes occur
Oxidation = Loss of electrons (LEO)
Zn Zn2+ + 2e-
Reduction = Gain of electrons (GER)
Cu2+ + 2e- Cu
LecturePLUS Timberlake 99
Balanced Red-Ox Equations
Combine the oxidation and reduction reactions to make
Loss of electrons = Gain of electrons
Zn + Cu2+ + 2e- Zn2+ + 2e- + Cu
Zn + Cu2+ Zn2+ + Cu
LecturePLUS Timberlake 99
Gain/Loss of Hydrogen
In organic and biological reactions
oxidation = Loss of H
reduction = Gain of H
LecturePLUS Timberlake 99
Learning Check R3
Identify the following as an 1) oxidation or a reduction process:
__A. Sn Sn4+ + 4e-
__B. Fe3+ + 1e- Fe2+
__C. Cl2 + 2e- 2Cl-
LecturePLUS Timberlake 99
Solution R3
Identify the following as an 1) oxidation or a reduction process:
1_ A. Sn Sn4+ + 4e-
2_ B. Fe3+ + 1e- Fe2+
2_ C. Cl2 + 2e- 2Cl-
LecturePLUS Timberlake 99
Learning Check R4
In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction
Ag+ + Cl- Ag + Cl
A. Which reactant is oxidized
1) Ag+ 2) Cl- 3) Ag
B. Which reactant is reduced?
1) Ag+ 2) Cl- 3) Cl
LecturePLUS Timberlake 99
Solution R4
In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction
Ag+ + Cl- Ag + Cl
A. Which reactant is oxidized
2) Cl- Cl- Cl + e-
B. Which reactant is reduced?
1) Ag+ Ag+ + e- Ag
