The standard cell potential ($$E^\ominus_{\text{cell}}$$) of a fuel cell based on the oxidation of methanol in air that has been used to power television relay station is measured as 1.21 V. The standard half cell reduction potential for $$O_2$$ ($$E^\circ_{O_2/H_2O}$$) is 1.229 V. Choose the correct statement:

The overall fuel‐cell reaction, carried out in acidic medium, is: $$CH_3OH + \tfrac{3}{2}O_2 \rightarrow CO_2 + 2H_2O$$.

In a galvanic cell, the standard cell potential is related to the standard reduction potentials of its two half-cells by the formula $$E^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode(reduction)}}$$ $$-(1)$$.

The problem supplies $$E^\circ_{\text{cell}} = 1.21\;V$$ and the cathodic reduction potential of oxygen, $$E^\circ_{O_2/H_2O} = 1.229\;V$$. Substituting in $$(1)$$, we find

$$E^\circ_{\text{anode(reduction)}} = 1.229\;V - 1.21\;V = 0.019\;V$$.

This value, $$0.019\;V = 19\;mV$$, is the standard reduction potential for the couple $$CO_2 + 6H^+ + 6e^- \rightarrow CH_3OH + H_2O$$, i.e. $$E^\circ_{CO_2/CH_3OH}$$.

Case A: “The standard half-cell reduction potential for the reduction of $$CO_2$$ is 19 mV.” — True, as just calculated.

Case B: “Oxygen is formed at the anode.” — False. Oxygen is consumed at the cathode and reduced to water; it is not evolved at the anode.

Case C: “Reactants are fed at one go to each electrode.” — False. In fuel cells the gaseous (or liquid) reactants are supplied continuously so that the cell can generate a steady current.

Case D: “Reduction of methanol takes place at the cathode.” — False. Methanol undergoes oxidation at the anode; the cathode hosts the reduction of oxygen.

Hence, only Option A is correct.