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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 38c
Chapter 20, Problem 38c

Balance each redox reaction occurring in acidic aqueous solution. c. MnO4–(aq) + Al(s) → Mn2+(aq) + Al3+(aq)

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Identify the oxidation and reduction half-reactions. MnO_4^- is reduced to Mn^{2+}, and Al is oxidized to Al^{3+}.
Balance the atoms other than O and H in each half-reaction. MnO_4^- to Mn^{2+} is already balanced for Mn, and Al to Al^{3+} is balanced for Al.
Balance the oxygen atoms by adding H_2O molecules. Add 4 H_2O to the right side of the reduction half-reaction to balance the 4 O atoms in MnO_4^-.
Balance the hydrogen atoms by adding H^+ ions. Add 8 H^+ to the left side of the reduction half-reaction to balance the 8 H atoms from the 4 H_2O.
Balance the charges by adding electrons. Add 5 e^- to the left side of the reduction half-reaction and 3 e^- to the right side of the oxidation half-reaction. Then, multiply the half-reactions by appropriate factors to equalize the number of electrons transferred.

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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 the other 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 for oxidation and reduction, balancing each half for atoms and charge, and then combining them while ensuring that the electrons lost in oxidation equal the electrons gained in reduction.

Acidic Aqueous Solution

In an acidic aqueous solution, the presence of hydrogen ions (H+) influences the balancing of redox reactions. When balancing reactions in acidic conditions, H+ ions and water (H2O) are often added to balance the hydrogen and oxygen atoms, respectively. This context is essential for correctly applying the balancing method to the given redox reaction.
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