Consider the following substances: Fe(s), PbO2(s), H+(aq), Al(s), Ag(s), Cr2O72-(aq). (a) Look at the E° values in Appendix D, and classify each substance as an oxidizing agent or a reducing agent.
Ch.19 - Electrochemistry
Chapter 19, Problem 79b
The following cell reactions occur spontaneously: (b) Which of these substances (A,A+,B,B+,C,C+) is the strongest oxidizing agent? Which is the strongest reducing agent?

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Step 1: Understand the terms 'oxidizing agent' and 'reducing agent'. An oxidizing agent is a substance that gains electrons and is reduced in a chemical reaction, while a reducing agent is a substance that loses electrons and is oxidized.
Step 2: Identify the half-reactions for each of the given substances (A, A+, B, B+, C, C+). Determine which species are being reduced and which are being oxidized.
Step 3: Use the standard reduction potential table to find the reduction potentials for each half-reaction. The substance with the highest reduction potential is the strongest oxidizing agent.
Step 4: Conversely, the substance with the lowest reduction potential (or highest oxidation potential) is the strongest reducing agent.
Step 5: Compare the reduction potentials of the given substances to determine which is the strongest oxidizing agent and which is the strongest reducing agent.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Oxidizing and Reducing Agents
An oxidizing agent is a substance that gains electrons in a chemical reaction, causing another substance to be oxidized. Conversely, a reducing agent loses electrons, leading to the reduction of another substance. The strength of these agents is determined by their ability to accept or donate electrons, respectively.
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Electrode Potentials
Electrode potentials, measured in volts, indicate the tendency of a species to be reduced. A higher (more positive) electrode potential signifies a stronger oxidizing agent, while a lower (more negative) potential indicates a stronger reducing agent. These values are essential for predicting the direction of redox reactions.
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Spontaneity of Reactions
A spontaneous reaction occurs without external intervention, often driven by changes in energy or entropy. In redox reactions, spontaneity can be assessed using the Gibbs free energy change, which is related to the electrode potentials of the oxidizing and reducing agents involved.
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