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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 1
Chapter 6 Chemical Reactions and Quantities
6.3
Oxidation–Reduction Reactions
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 2
Everyday Oxidation-Reduction Reactions
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)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 3
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)
Transfer of Electrons
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Oxidation and Reduction
4
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 5
Oxidized or Reduced?
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 6
Zn and Cu2+
oxidationZn(s) Zn2+(aq) + 2e-Silvery metal
reduction Cu2+(aq) + 2e- Cu(s)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 7
Electron Transfer from Zn to Cu2+
Oxidation: electron loss
Reduction: electron gain
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 8
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)
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 9
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)
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 10
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
Writing Oxidation and Reduction Reactions
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 11
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?
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 12
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
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 13
Learning Check
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. 14
Solution
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 reduced2H+ + 2e− H2
B. Al is oxidized 2Al 2Al3+ + 6e−
Br is reduced2Br + 2e− 2Br−
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Oxidation–Reduction in Biological SystemsIn 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
15
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Oxidation–Reduction in Biological Systems (continued)
16
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
Summary of Oxidation and Reduction
17