1. Chapter 6 Chemical Reactions and
Quantities
6.3
Oxidation–Reduction Reactions
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
1

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.
2

3. Transfer of Electrons
An oxidation–reduction reaction
 transfers electrons from one reactant to another
Oxidation Is a Loss of electrons
Zn(s)
Zn2+(aq) + 2e−
(OIL)
Reduction Is a Gain of electrons
Cu2+(aq) + 2e−
Cu(s)
(RIG)
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
3

4. Oxidation and Reduction
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
4

5. Oxidized or Reduced?
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
5

6. Zn and Cu2+
oxidation
Zn(s)
Silvery metal
Zn2+(aq) + 2ereduction
Cu2+(aq) + 2e-
General, Organic, and Biological Chemistry
Cu(s)
Copyright © 2010 Pearson Education, Inc.
6

7. Electron Transfer from Zn to Cu2+
Oxidation: electron loss
Reduction: electron gain
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
7

8. Learning Check
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−
General, Organic, and Biological Chemistry
2Cl−(aq)
Copyright © 2010 Pearson Education, Inc.
8

9. Solution
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−
General, Organic, and Biological Chemistry
2Cl−(aq)
Copyright © 2010 Pearson Education, Inc.
9

10. Writing Oxidation and Reduction
Reactions
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–
General, Organic, and Biological Chemistry
2F−(s)
reduction
Copyright © 2010 Pearson Education, Inc.
10

11. Learning Check
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.
11

12. Solution
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.
12

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)
General, Organic, and Biological Chemistry
2AlBr3(s)
Copyright © 2010 Pearson Education, Inc.
13

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 reduced
2H+ + 2e−
H2
B. Al is oxidized
Br is reduced
General, Organic, and Biological Chemistry
2Al
2Br + 2e−
2Al3+ + 6e−
2Br−
Copyright © 2010 Pearson Education, Inc.
14

15. Oxidation–Reduction in Biological
Systems
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.
15

16. Oxidation–Reduction in Biological
Systems (continued)
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
16

17. Summary of Oxidation and
Reduction
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
17