Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of SO₃^2-and MnO₄⁻ in the balanced reaction?
SO₃^2-(aq) + MnO₄⁻(aq) → SO₄^2-(aq) + MnO₂(s)

Question

Quizplus · Accepted Answer

1. Write the unbalanced equation:
SOS1U1B13S1U1B0S1U1P12-S1S1P0(aq) + MnOS1U1B14S1U1B0⁻(aq) → SOS1U1B14S1U1B0S1U1P12-S1S1P0(aq) + MnOS1U1B12S1U1B0(s)
2. Divide the equation into half-reactions (oxidation and reduction):
Oxidation: MnOS1U1B14S1U1B0⁻(aq) → MnOS1U1B12S1U1B0(s)
Reduction: SOS1U1B13S1U1B0S1U1P12-S1S1P0(aq) → SOS1U1B14S1U1B0S1U1P12-S1S1P0(aq)
3. Balance atoms other than H and O:
Oxidation: 4OH- + MnOS1U1B14S1U1B0⁻  → MnOS1U1B12S1U1B0 + 2H2O + 4e-
Reduction: SOS1U1B13S1U1B0S1U1P12 + 6e- → SOS1U1B14S1U1B0S1U1P12
4. Balance O by adding H2O
Oxidation: 4OH- + MnOS1U1B14S1U1B0⁻ → MnOS1U1B12S1U1B0 + 2H2O + 4e-
Reduction: 6e- + 6H2O + SOS1U1B13S1U1B0S1U1P12 → 6OH- + SOS1U1B14S1U1B0S1U1P12
5. Balance H+ by adding H+
Oxidation: 4OH- + MnOS1U1B14S1U1B0⁻ → MnOS1U1B12S1U1B0 + 2H2O + 4e-
Reduction: 6e- + 14H2O + SOS1U1B13S1U1B0S1U1P12 → 12OH- + SOS1U1B14S1U1B0S1U1P12 + 8H+
6. Check that charges are balanced
7. Add the two half-reactions and simplify to obtain the balanced equation:
SOS1U1B13S1U1B0S1U1P12-S1S1P0(aq) + 3MnOS1U1B14S1U1B0⁻(aq) + 14OH- → SOS1U1B14S1U1B0S1U1P12-S1S1P0(aq) + 3MnOS1U1B12S1U1B0(s) + 8H2O
The coefficients are: SOS1U1B13S1U1B0S1U1P12-S1S1P0 = 3, MnOS1U1B14S1U1B0⁻ = 3, and MnOS1U1B12S1U1B0 = 1. However, we are in basic solution, so we need to add 14 OH- ions to both sides to neutralize the H+ ions:
3 SOS1U1B13S1U1B0S1U1P12-S1S1P0 + 3 MnOS1U1B14S1U1B0⁻ + 14 OH- → 3 SOS1U1B14S1U1B0S1U1P12-S1S1P0 + MnOS1U1B12S1U1B0 + 8 H2O
Therefore, the coefficients are: SOS1U1B13S1U1B0S1U1P12-S1S1P0 = 3 and MnOS1U1B14S1U1B0⁻ = 3. Thus, the best choice is E (SOS1U1B13S1U1B0S1U1P12-S1S1P0 = 3, MnOS1U1B14S1U1B0⁻ = 3).

Balance the Following Redox Reaction If It Occurs in Basic