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Ch.20 - Electrochemistry
Tro - Chemistry: A Molecular Approach 6th Edition
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217Not the one you use?Change textbook
All textbooksTro 6th EditionCh.20 - ElectrochemistryProblem 40a
Chapter 20, Problem 40a

Balance each redox reaction occurring in acidic aqueous solution. a. I–(aq) + NO2–(aq) → I2(s) + NO(g) b. ClO4–(aq) + Cl–(aq) → ClO3–(aq) + Cl2(g)

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Identify the oxidation and reduction half-reactions. Iodide ions (I^-) are oxidized to iodine (I2), and nitrite ions (NO2^-) are reduced to nitric oxide (NO).
Write the oxidation half-reaction: I^- → I2. Balance the iodine atoms by adding a coefficient of 2 to I^-: 2I^- → I2.
Write the reduction half-reaction: NO2^- → NO. Balance the nitrogen atoms, which are already balanced, and then balance the oxygen atoms by adding H2O: NO2^- → NO + H2O.
Balance the hydrogen atoms in the reduction half-reaction by adding H^+ ions: NO2^- + 2H^+ → NO + H2O.
Balance the charges in each half-reaction by adding electrons. For the oxidation half-reaction, add 2 electrons to the right: 2I^- → I2 + 2e^-. For the reduction half-reaction, add 1 electron to the left: NO2^- + 2H^+ + e^- → NO + H2O.

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Key Concepts

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

Redox Reactions

Redox reactions, or reduction-oxidation reactions, involve the transfer of electrons between two species. In these reactions, one species is oxidized (loses electrons) while another is reduced (gains electrons). Understanding the oxidation states of the elements involved is crucial for identifying which species undergo oxidation and reduction.

Balancing Redox Reactions

Balancing redox reactions requires ensuring that both mass and charge are conserved. This often involves separating the reaction into half-reactions: one for oxidation and one for reduction. In acidic solutions, hydrogen ions (H+) and water (H2O) are typically added to balance the equation, along with electrons to balance the charge.

Acidic Aqueous Solutions

In acidic aqueous solutions, the presence of H+ ions influences the behavior of the reactants and products. The pH of the solution can affect the solubility and reactivity of certain species. When balancing redox reactions in such environments, it is essential to account for the H+ ions and water molecules that may be involved in the half-reactions.
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