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) + 3O 2 (g) 2Fe 2 O 3 (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) Zn 2+ (aq)+ 2 e  (loss of electrons) reduction is a gain of electrons (rig) Cu 2+ (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 Cu 2+ In a single replacement reaction, Zn(s) is oxidized to Zn 2+ (aq) Zn(s) Zn 2+ (aq) + 2 e  Cu 2+ (aq) is reduced to Cu(s) Cu 2+ (aq) + 2 e  Cu(s) The overall equation is written Zn(s) + Cu 2+ (aq) Zn 2+ (aq) + Cu(s)

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 6 Electron Transfer from Zn to Cu 2+ Oxidation of Zn: electron loss Reduction of Cu 2+ : electron gain

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 7 Identify each of the following as (O) oxidation or (R) reduction: __A. Sn(s) Sn 4+ (aq) + 4 e  __B. Fe 3+ (aq) + 1 e  Fe 2+ (aq) __C. Cl 2 (g) + 2 e  2Cl  (aq) Learning Check

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 8 Solution O A. Sn(s) Sn 4+ (aq) + 4 e  R B. Fe 3+ (aq) + 1 e  Fe 2+ (aq) R C. Cl 2 (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) + F 2 (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) + F 2 (g) 2CsF(aq) oxidation Cs(s) Cs + (aq) + 1 e  reduction F 2 (g) + 2 e  2F − (aq) Solution

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 11 In light-sensitive sunglasses, light initiates an 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 initiates an 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