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)?
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6. Chemical Quantities & Aqueous Reactions
Balancing Redox Reactions: Basic Solutions
Multiple Choice
Which of the following is the correctly balanced chemical equation for the reaction of ClO⁻(aq) with Cr(OH)₃(s) to form Cl⁻(aq) and CrO₄²⁻(aq) in a basic solution?
A
ClO⁻(aq) + Cr(OH)₃(s) + OH⁻(aq) → Cl⁻(aq) + CrO₄²⁻(aq) + H₂O(l)
B
ClO⁻(aq) + Cr(OH)₃(s) → Cl⁻(aq) + CrO₄²⁻(aq) + OH⁻(aq)
C
2 ClO⁻(aq) + Cr(OH)₃(s) + 3 OH⁻(aq) → 2 Cl⁻(aq) + CrO₄²⁻(aq) + H₂O(l)
D
3 ClO⁻(aq) + Cr(OH)₃(s) + 4 OH⁻(aq) → 3 Cl⁻(aq) + CrO₄²⁻(aq) + 2 H₂O(l)
Verified step by step guidance1
Identify the oxidation and reduction half-reactions. ClO⁻ is reduced to Cl⁻, and Cr(OH)₃ is oxidized to CrO₄²⁻.
Write the half-reaction for the reduction of ClO⁻ to Cl⁻: ClO⁻(aq) + 2 e⁻ + H₂O(l) → Cl⁻(aq) + 2 OH⁻(aq).
Write the half-reaction for the oxidation of Cr(OH)₃ to CrO₄²⁻: Cr(OH)₃(s) + 5 OH⁻(aq) → CrO₄²⁻(aq) + 3 H₂O(l) + 3 e⁻.
Balance the electrons between the two half-reactions by multiplying the reduction half-reaction by 3 and the oxidation half-reaction by 2.
Combine the balanced half-reactions, ensuring that all species are balanced, including electrons, to obtain the overall balanced equation: 3 ClO⁻(aq) + Cr(OH)₃(s) + 4 OH⁻(aq) → 3 Cl⁻(aq) + CrO₄²⁻(aq) + 2 H₂O(l).
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