Ch.20 - Electrochemistry

Problem 45a,b,c

Chapter 20, Problem 45a,b,c

By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (a) Cl₂(g), (b) MnO₄^- (aq, acidic solution), (c) Ba(s)

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Identify the half-reaction for \( \text{MnO}_4^- \) in an acidic solution from Appendix E, which typically involves the reduction of \( \text{MnO}_4^- \) to \( \text{Mn}^{2+} \).

Write the balanced half-reaction for the reduction of \( \text{MnO}_4^- \) in acidic solution: \( \text{MnO}_4^- + 8\text{H}^+ + 5\text{e}^- \rightarrow \text{Mn}^{2+} + 4\text{H}_2\text{O} \).

Look up the standard reduction potential \( E^0 \) for this half-reaction in Appendix E.

Determine if the \( E^0 \) value is positive, which indicates that \( \text{MnO}_4^- \) is a strong oxidizing agent (oxidant) because it readily gains electrons.

Conclude that if the \( E^0 \) value is positive, \( \text{MnO}_4^- \) is likely to serve as an oxidant in an acidic solution.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Oxidation and Reduction

Oxidation and reduction are chemical processes that involve the transfer of electrons between substances. Oxidation refers to the loss of electrons, while reduction involves the gain of electrons. In redox reactions, one species is oxidized and another is reduced, which is essential for understanding the roles of oxidants and reductants.

Oxidizing and Reducing Agents

An oxidizing agent, or oxidant, is a substance that causes another substance to be oxidized by accepting electrons, while a reducing agent, or reductant, donates electrons to reduce another substance. Identifying whether a substance acts as an oxidant or reductant is crucial for predicting the outcome of redox reactions.

Standard Reduction Potentials

Standard reduction potentials are measured values that indicate the tendency of a species to gain electrons and be reduced. These values, typically found in tables, help determine the strength of oxidizing and reducing agents. A higher standard reduction potential suggests a stronger oxidant, while a lower value indicates a stronger reductant.

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Standard Reduction Potentials

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Textbook Question

From each of the following pairs of substances, use data in Appendix E to choose the one that is the stronger reducing agent: (a) Fe(s) or Mg(s) (b) Ca(s) or Al(s) (c) H₂(g, acidic solution) or H₂S(g)

Textbook Question

From each of the following pairs of substances, use data in Appendix E to choose the one that is the stronger reducing agent: (d) BrO3-1aq2 or IO3-1aq2

Textbook Question

By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (d) Zn(s)

Textbook Question

Is each of the following substances likely to serve as an oxidant or a reductant: (a) Ce³⁺(aq) (b) Ca(s) (c) ClO₃^-(aq) (d) N₂O₅(g)?

Textbook Question

(a) Assuming standard conditions, arrange the following in order of increasing strength as oxidizing agents in acidic solution: Cr₂O₇^2-, H₂O₂, Cu²⁺, Cl₂, O₂.

By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (a) Cl2(g), (b) MnO4- (aq, acidic solution), (c) Ba(s)

Verified video answer for a similar problem:

Key Concepts

Oxidation and Reduction

Oxidizing and Reducing Agents

Standard Reduction Potentials

By using the data in Appendix E, determine whether each of the following substances is likely to serve as an oxidant or a reductant: (a) Cl₂(g), (b) MnO₄^- (aq, acidic solution), (c) Ba(s)