Transcript CH_5_5_Oxidation_Reduction_Reactions-1

Chapter 5
Chemical Quantities and Reactions
1
5.5
Oxidation−Reduction Reactions
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
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Oxidation−Reduction Reactions
2
An oxidation–reduction reaction
• provides us with energy from food
• provides electrical energy in batteries
• occurs when iron rusts:
4Fe(s) + 3O2(g)
2Fe2O3(s)
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Oxidation−Reduction
3
In an oxidation–reduction reaction, electrons are
transferred from one substance to another.
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Oxidation−Reduction
4
Reduced
Oxidized
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
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Oxidation and Reduction
5
2Cu(s) + O2(g)
2CuO
OIL RIG
Oxidation is loss of electrons.
2Cu(s)
2Cu2+(s) + 4e−
Reduction is gain of electrons.
O2(g) + 4e−
2O2− (s)
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
The green patina on
copper is due to
oxidation
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Zn replaces Cu2+
6
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Zn Transfers Electrons to Cu2+
7
OIL
Oxidation is losing electrons.
RIG
Reduction is gaining electrons.
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Learning Check
8
Identify each of the following as oxidation or reduction:
Sn4+(aq) + 4e−
__A.
Sn(s)
__B.
Fe3+(aq) + 1e−
__C.
Cl2(g) + 2e−
Fe2+(aq)
2Cl− (aq)
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
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Solution
9
Identify each of the following as oxidation or reduction:
Sn(s)
Sn4+(aq) + 4e−
Oxidation
__A.
Reduction
__B. Fe3+(aq) + 1e−
Reduction
__C.
Cl2(g) + 2e−
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Fe2+(aq)
2Cl− (aq)
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Learning Check
10
In light-sensitive sunglasses, UV light initiates an
oxidation–reduction reaction.
UV light
2Ag+ + 2Cl−
2Ag + Cl2
A. Which reactant is oxidized?
B. Which reactant is reduced?
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
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Solution
11
In light-sensitive sunglasses, UV light initiates an
oxidation-reduction reaction.
uv light
2Ag+ + 2Cl−
2Ag + Cl2
A. Which reactant is oxidized? 2Cl−
Cl2 + 2e−
B. Which reactant is reduced? 2Ag+ + 2e−
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
2Ag
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Oxidation–Reduction in Biological
Systems
12
The oxidation of a typical biochemical molecule can
involve the transfer of two hydrogen atoms (or 2H+ and
2e−) to a proton acceptor such as the coenzyme FAD (flavin
adenine dinucleotide).
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Characteristics of Oxidation and
Reduction
13
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Characteristics of Oxidation and
Reduction
14
Methyl alcohol
formaldehyde Oxidation (loss of H as
hydrogen gas)
CH3OH
Formaldehyde
2H2CO + O2
H2CO + 2H2
formic acid
2H2CO2
Oxidation (addition of O)
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.