Q.In hydrogen-oxygen fuel cell the carbon rods are immersed in hot aqueous solution of —

The H$_2$–O$_2$ fuel cell uses aqueous KOH as the electrolyte.

In a hydrogen–oxygen fuel cell, H$_2$ gas is oxidised at the anode and O$_2$ gas is reduced at the cathode, with an aqueous alkaline electrolyte (KOH solution) carrying OH$^-$ ions between the porous carbon electrodes:

Anode: $2H_2 + 4OH^- \rightarrow 4H_2O + 4e^-$

Cathode: $O_2 + 2H_2O + 4e^- \rightarrow 4OH^-$

Overall: $2H_2 + O_2 \rightarrow 2H_2O$

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The $H_2$–$O_2$ fuel cell uses concentrated aqueous KOH as its electrolyte.

In the hydrogen–oxygen fuel cell, two porous carbon electrodes (with catalysts) are immersed in hot, concentrated aqueous potassium hydroxide (KOH) solution, which serves as the electrolyte carryi …