Question

Shown below are the reactions occurring in the direct methanol fuel cell (DMFC).

I 2 CH3OH(aq) + 2 H2O(l) → 2 CO2(g) +12 H+(aq) +12 e-

II 3 O2(g) + 12 H+(aq) + 12 e- → 6 H2O(l) Overall 2 CH3OH(aq) + 3 O2(g) → 2 CO2(g) + 4 H2O(l)

Which is the anode reaction, and what is being oxidized in the overall reaction?

II, O2

I, H2O

II, H+

IV, CH3OH

Answer 1

I 2 CH3OH(aq) + 2 H2O(l) → 2 CO2(g) +12 H+(aq) +12 e-   oxidation reaction

in this reaction carbon oxidation number increases from -2 to +4 . CH3OH is oxidized

I 2 CH3OH(aq) + 2 H2O(l) → 2 CO2(g) +12 H+(aq) +12 e-   oxidation reaction

II 3 O2(g) + 12 H+(aq) + 12 e- → 6 H2O(l)                               reduction reaction

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Overall 2 CH3OH(aq) + 3 O2(g) → 2 CO2(g) + 4 H2O(l)

IV, CH3OH