Chapter 19: Oxidation-Reduction Reactions

Section 3: Oxidizing and Reducing Agents

Objectives

• Relate chemical activity to oxidizing and reducing strength.

• Explain the concept of disproportionation.

• A reducing agent is a substance that has the potential to cause another substance to be reduced.

• An oxidizing agent is a substance that has the potential to cause another substance to be oxidized.

Strengths of Oxidizing and Reducing Agents

Strengths of Oxidizing and Reducing Agents, continued

Strengths of Oxidizing and Reducing Agents, continued

• Different substances can be compared and rated by their relative potential as reducing and oxidizing agents.

• The negative ion of a strong oxidizing agent is a weak reducing agent.

• The positive ion of a strong reducing agent is a weak oxidizing agent.

Disproportionation

• A process in which a substance acts as both an oxidizing agent and a reducing agent is called disproportionation.

• A substance that undergoes disproportionation is both self-oxidizing and self-reducing.

› example: Hydrogen peroxide is both oxidized and reduced

-1 -1 0 2 2 2 22H O 2H O O