Chapter 5
Chemical Reactions and
Quantities
Types of Reactions
Oxidation-Reduction Reactions
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Type of Reactions
Chemical reactions are classified into
four general types
 Combination
 Decomposition
 Single Replacement
 Double Replacement
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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
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Decomposition
One substance is broken down (split)
into two or more simpler substances.
AB
A + B
2HgO
2Hg + O2
2KClO3
2KCl + 3 O2
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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
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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
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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
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Double Replacement
Two elements in reactants take the place
of each other
AB + CD
AD + CB
AgNO3 + NaCl
AgCl + NaNO3
ZnS
ZnCl2 + H2S
+ 2HCl
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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
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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
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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
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Learning Check R3
Balance the combustion equation
___C5H12 + ___O2
___CO2 + ___H2O
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Solution R3
Balance the combustion equation
1 C5H12 + 8 O2
5 CO2 + 6 H2O
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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
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Requirements for OxidizationReduction
Electrons are transferred
Two processes occur
Oxidation = Loss of electrons (LEO)
Zn
Zn2+ + 2e-
Reduction = Gain of electrons (GER)
Cu2+ + 2eLecturePLUS Timberlake 99
Cu
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
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Gain/Loss of Hydrogen
In organic and biological reactions
oxidation = Loss of H
reduction = Gain of H
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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-
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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-
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Learning Check R4
In light-sensitive sunglasses, UV light
initiates an oxidation-reduction reaction
Ag+ + ClAg + Cl
A. Which reactant is oxidized
1) Ag+
2) Cl3) Ag
B. Which reactant is reduced?
1) Ag+
2) Cl3) Cl
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Solution R4
In light-sensitive sunglasses, UV light
initiates an oxidation-reduction reaction
Ag+ + ClAg + Cl
A. Which reactant is oxidized
2) ClClCl + eB. Which reactant is reduced?
1) Ag+
Ag+ + eAg
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