General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Transfer of Electrons
1
An oxidation–reduction reaction transfers electrons from one reactant to
another
Oxidation Is a Loss of electrons (OIL)
Zn(s) Zn2+(aq) + 2e
Reduction Is a Gain of electrons (RIG)Cu2+(aq) + 2e Cu(s)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Oxidation and Reduction
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Oxidized or Reduced?
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Zn and Cu2+
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oxidationZn(s) Zn2+(aq) + 2e-Silvery metal
reduction Cu2+(aq) + 2e- Cu(s)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Electron Transfer from Zn to Cu2+
Oxidation: electron loss
Reduction: electron gain
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Learning Check
6
Identify each of the following as:1) oxidation or 2) reduction
__A. Sn(s) Sn4+(aq) + 4e−
__B. Fe3+(aq) + 1e− Fe2+(aq)
__C. Cl2(g) + 2e− 2Cl−(aq)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Solution
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Identify each of the following as:1) oxidation or 2) reduction
1 A. Sn(s) Sn4+(aq) + 4e−
2 B. Fe3+(aq) + 1e− Fe2+(aq)
2 C. Cl2(g) + 2e− 2Cl−(aq)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Writing Oxidation and Reduction Reactions
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Write the separate oxidation and reduction reactions for the following equation.
2Cs(s) + F2(g) 2CsF(s)
Each cesium atom loses an electron to form a cesium ion.
2Cs(s) 2Cs+(s) + 2e− oxidation
Each fluorine atom gains an electron to form a fluoride ion.
F2(s) + 2e– 2F−(s) reduction
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Learning Check
9
In light-sensitive sunglasses, UV light initiates an
oxidation–reduction reaction. uv light
Ag+ + Cl− Ag + Cl
A. Which reactant is oxidized?
B. Which reactant is reduced?
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Solution
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In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction. uv light
Ag+ + Cl− Ag + Cl
A. Which reactant is oxidized? Cl − Cl− Cl + 1e−
B. Which reactant is reduced? Ag+ Ag+ + 1e− Ag
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Learning Check
11
Identify the substances that are oxidized and reduced in
each of the following reactions:A. Mg(s) + 2H+(aq) Mg2+(aq) + H2(g)
B. 2Al(s) + 3Br2(g) 2AlBr3(s)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Solution
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Identify the substances that are oxidized and reduced in
each of the following reactions:A. Mg is oxidized Mg(s) Mg2+
(aq) + 2e−
H+ is reduced 2H+ + 2e− H2
B. Al is oxidized 2Al 2Al3+ + 6e−
Br is reduced 2Br + 2e− 2Br−
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Oxidation–Reduction in Biological Systems
13
In biological systems, oxidation may involve the loss of H the gain of O
In biological systems, reduction may involve the gain of H the loss of O
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Oxidation–Reduction in Biological Systems (continued)
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Summary of Oxidation and Reduction
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