A voltaic cell consists of a strip of cadmium metal in a solution of Cd(NO3)2 in one beaker, and in the other beaker a platinum electrode is immersed in a NaCl solution, with Cl2 gas bubbled around the electrode. A salt bridge connects the two beakers. (a) Which electrode serves as the anode, and which as the cathode? (b) Does the Cd electrode gain or lose mass as the cell reaction proceeds? (c) Write the equation for the overall cell reaction.
Ch.20 - Electrochemistry
Chapter 20, Problem 43d
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

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Identify the half-reactions for both BrO3- (bromate ion) and IO3- (iodate ion) in their reduction forms. This involves finding the reactions where these ions gain electrons to form their respective reduced states.
Consult Appendix E or a standard reduction potential table to find the standard reduction potentials (E°) for both BrO3- and IO3-. These values indicate the tendency of each ion to gain electrons.
Compare the standard reduction potentials of the two half-reactions. The substance with the more negative E° value is the stronger reducing agent, as it indicates a greater tendency to donate electrons.
Remember that a stronger reducing agent has a greater ability to reduce other substances, meaning it is more easily oxidized itself.
Conclude which ion, BrO3- or IO3-, is the stronger reducing agent based on the comparison of their standard reduction potentials.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reducing Agents
A reducing agent is a substance that donates electrons in a chemical reaction, thereby reducing another substance. The strength of a reducing agent is determined by its ability to lose electrons easily. Stronger reducing agents have a greater tendency to undergo oxidation, which is the loss of electrons.
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Oxidizing and Reducing Agents
Standard Reduction Potentials
Standard reduction potentials (E°) are measured values that indicate the tendency of a species to gain electrons and be reduced. These values are typically found in tables and are used to compare the strength of different oxidizing and reducing agents. A more negative E° value indicates a stronger reducing agent, as it is more likely to lose electrons.
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Standard Reduction Potentials
Oxidation States
Oxidation states (or numbers) represent the degree of oxidation of an atom in a compound. They help in determining how many electrons are gained or lost during a reaction. Understanding the oxidation states of the elements in the substances being compared is crucial for identifying which one acts as the stronger reducing agent.
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Oxidation Numbers
Related Practice
Textbook Question
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
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)
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)