Multiple Choice
Which of the following is the correctly balanced chemical equation for the combustion of glucose (C6H12O6)?
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3. Chemical Reactions
Balancing Chemical Equations
Multiple Choice
Given the following unbalanced half-reactions:1) Fe^{2+} → Fe^{3+} + e^-2) MnO_4^- + 8H^+ + 5e^- → Mn^{2+} + 4H_2OWhich of the following is the correctly balanced overall reaction?
A
5Fe^{2+} + MnO_4^- + 8H^+ → 5Fe^{3+} + Mn^{2+} + 4H_2O
B
5Fe^{2+} + MnO_4^- → 5Fe^{3+} + Mn^{2+} + 4H_2O
C
Fe^{2+} + MnO_4^- + H^+ → Fe^{3+} + Mn^{2+} + H_2O
D
Fe^{2+} + MnO_4^- + 8H^+ → Fe^{3+} + Mn^{2+} + 4H_2O
Verified step by step guidance1
Identify the two half-reactions given: the oxidation half-reaction is \(\mathrm{Fe^{2+} \rightarrow Fe^{3+} + e^-}\) and the reduction half-reaction is \(\mathrm{MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O}\).
Balance the electrons lost in the oxidation half-reaction with the electrons gained in the reduction half-reaction. Since the oxidation half-reaction produces 1 electron and the reduction half-reaction consumes 5 electrons, multiply the entire oxidation half-reaction by 5 to equalize the electrons.
Write the multiplied oxidation half-reaction: \(\mathrm{5Fe^{2+} \rightarrow 5Fe^{3+} + 5e^-}\) and keep the reduction half-reaction as is.
Add the two half-reactions together, canceling out the electrons on both sides to get the overall balanced reaction.
Verify that atoms and charges are balanced on both sides of the overall reaction: \(\mathrm{5Fe^{2+} + MnO_4^- + 8H^+ \rightarrow 5Fe^{3+} + Mn^{2+} + 4H_2O}\).
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