Textbook Question
Use the data in Appendix D to predict whether the following reactions can occur under standard-state conditions. (a) Oxidation of Sn2+(aq) by Br2(aq)
Ch.19 - Electrochemistry
Chapter 19, Problem 80d
Use the data in Appendix D to predict whether the following reactions can occur under standard-state conditions. (d) Reduction of I2(s) by H2SO3(aq)
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Identify the half-reactions involved in the process. The reduction of \( \text{I}_2(s) \) to \( \text{I}^- \) and the oxidation of \( \text{H}_2\text{SO}_3(aq) \) to \( \text{SO}_4^{2-} \).
Write the standard reduction potentials for each half-reaction from Appendix D. The reduction potential for \( \text{I}_2(s) + 2e^- \rightarrow 2\text{I}^- \) and the oxidation potential for \( \text{H}_2\text{SO}_3(aq) + \text{H}_2\text{O}(l) \rightarrow \text{SO}_4^{2-} + 4\text{H}^+ + 2e^- \).
Reverse the oxidation half-reaction to express it as a reduction reaction and change the sign of its potential.
Calculate the standard cell potential \( E^\circ_{\text{cell}} \) by adding the standard reduction potential of the iodine reduction and the reversed oxidation potential of the \( \text{H}_2\text{SO}_3 \) reaction.
Determine if the reaction is spontaneous under standard conditions by checking if \( E^\circ_{\text{cell}} \) is positive. If it is, the reaction can occur under standard-state conditions.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Standard-State Conditions
Standard-state conditions refer to a set of specific conditions used to measure the properties of substances. These typically include a temperature of 25°C (298 K), a pressure of 1 atm, and concentrations of 1 M for solutions. Understanding these conditions is crucial for predicting the feasibility of chemical reactions, as they provide a baseline for comparing thermodynamic data.
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Standard Reduction Potentials
Reduction and Oxidation Reactions
Reduction and oxidation (redox) reactions involve the transfer of electrons between species. In a reduction reaction, a substance gains electrons, leading to a decrease in oxidation state. Identifying the oxidizing and reducing agents in a reaction is essential for predicting whether a reaction can occur, as it determines the direction of electron flow and the overall feasibility of the reaction.
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01:53Oxidation and Reduction Reactions
Electrochemical Series
The electrochemical series is a list of standard electrode potentials for various half-reactions, which helps predict the spontaneity of redox reactions. A more positive electrode potential indicates a greater tendency to be reduced. By comparing the standard potentials of I<sub>2</sub> and H<sub>2</sub>SO<sub>3</sub>, one can determine if the reduction of iodine by sulfurous acid is thermodynamically favorable under standard-state conditions.
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02:46Electrochemical Cells
Related Practice
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