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Basic Chemistry Copyright © 2011 Pearson Education, Inc.1
Chapter 15 Oxidation-Reduction: Transfer of Electrons
15.1 Oxidation and Reduction
Rust forms on a set of tools when oxygen reacts with iron.
Basic Chemistry Copyright © 2011 Pearson Education, Inc.2
Oxidation and Reduction
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) Rust forms on a set of tools when oxygen reacts with iron.
Basic Chemistry Copyright © 2011 Pearson Education, Inc.3
In an oxidation-reduction reaction, one reactant loses electrons and another reactant gains electrons.• electrons are transferred from one reactant to
another• oxidation is a loss of electrons (oil)
Zn(s) Zn2+(aq)+ 2 e (loss of electrons)• reduction is a gain of electrons (rig)
Cu2+(aq) + 2 e Cu(s) (gain of electrons)
Electron Loss and Gain
Basic Chemistry Copyright © 2011 Pearson Education, Inc.4
Examples of Oxidized and Reduced Substances
Basic Chemistry Copyright © 2011 Pearson Education, Inc.5
Zn and Cu2+
In a single replacement reaction,• Zn(s) is oxidized to Zn2+(aq)
Zn(s) Zn2+(aq) + 2 e
• Cu2+(aq) is reduced to Cu(s) Cu2+(aq) + 2 e Cu(s)• The overall equation is written Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s)
Basic Chemistry Copyright © 2011 Pearson Education, Inc.6
Electron Transfer from Zn to Cu2+
Oxidation of Zn: electron loss
Reduction of Cu2+: electron gain
Basic Chemistry Copyright © 2011 Pearson Education, Inc.7
Identify each of the following as (O) oxidation or (R) reduction:
__A. Sn(s) Sn4+(aq) + 4 e
__B. Fe3+(aq) + 1 e Fe2+(aq)
__C. Cl2(g) + 2 e 2Cl(aq)
Learning Check
Basic Chemistry Copyright © 2011 Pearson Education, Inc.8
Solution
O A. Sn(s) Sn4+(aq) + 4 e
R B. Fe3+(aq) + 1 e Fe2+(aq)
R C. Cl2(g) + 2 e 2Cl(aq)
Basic Chemistry Copyright © 2011 Pearson Education, Inc.9
Write the oxidation reaction and the reduction reaction for the following: 2Cs(s) + F2(g) 2CsF(aq)
Learning Check
Basic Chemistry Copyright © 2011 Pearson Education, Inc.10
Write the oxidation reaction and the reduction reaction for the following:2Cs (s) + F2(g) 2CsF(aq)
oxidation Cs(s) Cs+(aq) + 1 e reduction F2(g) + 2 e 2F−(aq)
Solution
Basic Chemistry Copyright © 2011 Pearson Education, Inc.11
In light-sensitive sunglasses, light initiatesan oxidation-reduction reaction. light
Ag+(aq) + Cl−(aq) Ag(s) + Cl(s)
A. Which reactant is oxidized?
B. Which reactant is reduced?
Learning Check
Basic Chemistry Copyright © 2011 Pearson Education, Inc.12
In light-sensitive sunglasses, light initiatesan oxidation-reduction reaction. light
Ag+(aq) + Cl−(aq) Ag(s) + Cl(s)
A. Which reactant is oxidized? Cl−(aq) Cl(s) + 1 e
B. Which reactant is reduced? Ag+(aq) + 1 e− Ag(s)
Solution