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Ch.19 - Electrochemistry
McMurry - Chemistry 8th Edition
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All textbooksMcMurry 8th EditionCh.19 - ElectrochemistryProblem 46b
Chapter 19, Problem 46b

Write unbalanced oxidation and reduction half-reactions for the following processes. . (b) H2O2(aq) + Fe2+(aq) → Fe3+(aq) + H2O(l)

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Identify the species being oxidized and reduced. In this reaction, Fe^{2+} is oxidized to Fe^{3+}, and H_2O_2 is reduced to H_2O.
Write the oxidation half-reaction. For the oxidation of Fe^{2+} to Fe^{3+}, the half-reaction is: Fe^{2+} \(\rightarrow\) Fe^{3+} + e^-.
Write the reduction half-reaction. For the reduction of H_2O_2 to H_2O, the half-reaction is: H_2O_2 + 2e^- \(\rightarrow\) 2H_2O.
Ensure that the electrons lost in the oxidation half-reaction equal the electrons gained in the reduction half-reaction. In this case, multiply the oxidation half-reaction by 2 to balance the electrons.
Combine the balanced half-reactions to form the overall balanced redox reaction, ensuring that the number of electrons lost equals the number of electrons gained.

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 species. Oxidation refers to the loss of electrons, resulting in an increase in oxidation state, while reduction involves the gain of electrons, leading to a decrease in oxidation state. These processes always occur simultaneously in a redox reaction, where one species is oxidized and another is reduced.
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Oxidation and Reduction Reactions

Half-Reactions

Half-reactions are a way to represent oxidation and reduction processes separately. In a half-reaction, the species undergoing oxidation is shown with its electrons lost, while the species undergoing reduction is shown with its electrons gained. This method simplifies the analysis of redox reactions and helps in balancing the overall reaction by ensuring that the number of electrons lost equals the number of electrons gained.

Balancing Redox Reactions

Balancing redox reactions involves ensuring that both mass and charge are conserved in the reaction. This is typically done by balancing the half-reactions for the number of atoms and the total charge. In acidic or basic solutions, additional steps may include adding H<sub>2</sub>O, H<sup>+</sup>, or OH<sup>-</sup> ions to achieve balance, which is crucial for accurately representing the chemical changes occurring in the reaction.
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Balance the half-reactions in Problem 19.42, assuming that they occur in acidic solution.

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Balance the following half-reactions. (a) (acidic) Cr2O72-(aq) → Cr3+(aq)

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Balance the following half-reactions. (b) (basic) CrO42-(aq) → Cr(OH)4-(aq)

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Balance the half-reactions in Problem 19.43, assuming that they occur in basic solution.

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