dr seemal jelani chem-100 chemical reactions and quantities types of reactions oxidation-reduction...
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Dr Seemal Jelani Chem-100
Chemical Reactions and
Quantities
Types of Reactions
Oxidation-Reduction Reactions
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Dr Seemal Jelani Chem-100
Type of Reactions
Chemical reactions are classified into four general types
Combination
Decomposition
Single Replacement
Double Replacement
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Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
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 + 2HCl ZnCl2 + H2S
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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 + 3CO04/21/23 9
Dr Seemal Jelani Chem-100
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 + 3CO04/21/23 10
Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
Learning Check R3
Balance the combustion equation
___C5H12 + ___O2 ___CO2 + ___H2O
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Dr Seemal Jelani Chem-100
Solution R3
Balance the combustion equation
1 C5H12 + 8 O2 5 CO2 + 6 H2O
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Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
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
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Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
Gain/Loss of Hydrogen
In organic and biological reactions
oxidation = Loss of H
reduction = Gain of H
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Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
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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Dr Seemal Jelani Chem-100
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
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Dr Seemal Jelani Chem-100
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
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