Multiple Choice
Balance the following redox reaction if it occurs in acidic solution. What is the coefficient in front of SO3^2- in the balanced reaction? SO3^2- (aq) + MnO4^- (aq) → SO4^2- (aq) + Mn^2+ (aq)
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6. Chemical Quantities & Aqueous Reactions
Balancing Redox Reactions: Acidic Solutions
Multiple Choice
What is the balanced redox reaction for Cu(s) + NO3⁻(aq) → Cu²⁺(aq) + NO2(g) in an acidic solution?
A
Cu(s) + 2NO3⁻(aq) + 4H⁺(aq) → Cu²⁺(aq) + 2NO2(g) + 2H2O(l)
B
2Cu(s) + NO3⁻(aq) + 4H⁺(aq) → 2Cu²⁺(aq) + NO2(g) + 2H2O(l)
C
3Cu(s) + 2NO3⁻(aq) + 8H⁺(aq) → 3Cu²⁺(aq) + 2NO2(g) + 4H2O(l)
D
Cu(s) + NO3⁻(aq) + 2H⁺(aq) → Cu²⁺(aq) + NO2(g) + H2O(l)
Verified step by step guidance1
Identify the oxidation and reduction half-reactions. Copper (Cu) is oxidized to Cu²⁺, and nitrate (NO3⁻) is reduced to nitrogen dioxide (NO2).
Write the oxidation half-reaction: Cu(s) → Cu²⁺(aq) + 2e⁻. This shows the loss of electrons by copper.
Write the reduction half-reaction: NO3⁻(aq) + 2e⁻ + 2H⁺(aq) → NO2(g) + H2O(l). This shows the gain of electrons by nitrate, forming nitrogen dioxide and water.
Balance the electrons transferred in both half-reactions. Multiply the oxidation half-reaction by 3 and the reduction half-reaction by 2 to balance the electrons.
Combine the balanced half-reactions, ensuring that the number of electrons lost equals the number gained, and balance the remaining atoms. The final balanced equation is: 3Cu(s) + 2NO3⁻(aq) + 8H⁺(aq) → 3Cu²⁺(aq) + 2NO2(g) + 4H2O(l).
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