Textbook Question
(a) Write a chemical equation that describes the attack of acid rain on limestone, CaCO3.
3. Chemical Reactions
Balancing Chemical Equations
Multiple Choice
Which of the following is the correct balanced equation for the reaction between aluminum and permanganate ions in an aqueous solution?
A
2Al(s) + 3MnO4⁻(aq) → 3MnO2(s) + 2Al(OH)3(aq)
B
2Al(s) + 3MnO4⁻(aq) + 4H2O(l) → 3MnO2(s) + 2Al(OH)4⁻(aq)
C
2Al(s) + 3MnO4⁻(aq) + 2H2O(l) → 3MnO2(s) + 2Al(OH)3(aq)
D
Al(s) + MnO4⁻(aq) + 2H2O(l) → MnO2(s) + Al(OH)4⁻(aq)
Verified step by step guidance1
Identify the reactants and products in the given chemical reaction. The reactants are aluminum (Al) and permanganate ions (MnO4⁻) in an aqueous solution, and the products include manganese dioxide (MnO2) and aluminum hydroxide species.
Determine the oxidation states of the elements involved in the reaction. Aluminum (Al) starts in the 0 oxidation state and is oxidized, while manganese in permanganate (MnO4⁻) is reduced from +7 to +4 in MnO2.
Write the half-reactions for oxidation and reduction. The oxidation half-reaction involves Al being oxidized to Al(OH)4⁻, and the reduction half-reaction involves MnO4⁻ being reduced to MnO2.
Balance each half-reaction for mass and charge. For the oxidation half-reaction, balance aluminum and hydroxide ions. For the reduction half-reaction, balance manganese, oxygen, and hydrogen ions, using water molecules and hydrogen ions as needed.
Combine the balanced half-reactions, ensuring that the electrons lost in the oxidation half-reaction equal the electrons gained in the reduction half-reaction. This will give you the balanced overall equation for the reaction.
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