Multiple Choice
Balance the following redox reaction in a basic solution. What is the coefficient in front of Br^- in the balanced reaction?MnO4^- (aq) + Br^- (aq) → BrO3^- (aq) + MnO2 (s)
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6. Chemical Quantities & Aqueous Reactions
Balancing Redox Reactions: Basic Solutions
Multiple Choice
Which of the following is the correctly balanced redox reaction occurring in basic solution for ClO⁻(aq) + Cr(OH)₄⁻(aq) → CrO₄²⁻(aq) + Cl⁻(aq)?
A
ClO⁻(aq) + Cr(OH)₄⁻(aq) + OH⁻(aq) → CrO₄²⁻(aq) + Cl⁻(aq) + H₂O(l)
B
2 ClO⁻(aq) + Cr(OH)₄⁻(aq) + 2 OH⁻(aq) → CrO₄²⁻(aq) + 2 Cl⁻(aq) + 2 H₂O(l)
C
3 ClO⁻(aq) + 2 Cr(OH)₄⁻(aq) + 4 OH⁻(aq) → 2 CrO₄²⁻(aq) + 3 Cl⁻(aq) + 4 H₂O(l)
D
ClO⁻(aq) + 2 Cr(OH)₄⁻(aq) + 3 OH⁻(aq) → 2 CrO₄²⁻(aq) + Cl⁻(aq) + 3 H₂O(l)
Verified step by step guidance1
Identify the oxidation and reduction half-reactions. In this case, ClO⁻ is reduced to Cl⁻, and Cr(OH)₄⁻ is oxidized to CrO₄²⁻.
Balance the atoms other than O and H in each half-reaction. For the reduction half-reaction, balance Cl atoms. For the oxidation half-reaction, balance Cr atoms.
Balance the oxygen atoms by adding H₂O molecules to the side that needs oxygen. For the reduction half-reaction, add H₂O to the side with Cl⁻. For the oxidation half-reaction, add H₂O to the side with CrO₄²⁻.
Balance the hydrogen atoms by adding OH⁻ ions to the side that needs hydrogen. Since the solution is basic, add OH⁻ to both sides to neutralize the H⁺ ions formed.
Combine the balanced half-reactions, ensuring that the electrons cancel out. Adjust coefficients to ensure that the number of electrons lost in oxidation equals the number gained in reduction.
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