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Question
Explain the function of H2 – O2 fuel cell.
Solution
In this case, hydrogen act as a fuel and oxygen as an oxidant and the electrolyte is aqueous KOH maintained at 200°C and 20 – 40 atm. Porous graphite electrode containing Ni and NiO serves as the inert electrodes. Hydrogen and oxygen gases are bubbled through the anode and cathode, respectively.
Oxidation occurs at the anode:
\[\ce{2H2_{(g)} + 4OH^-_{( aq)} -> 4H2O_{(l)} + 4e^-}\]
Reduction occurs at the cathode:
\[\ce{O2_{(g)} + 2H2O_{(l)} + 4e^- -> 4OH^-_{( aq)}}\]
The overall reaction is \[\ce{2H2_{(g)} + O2_{(g)} -> 2H2O_{(l)}}\]
The above reaction is the same as the hydrogen combustion reaction, however, they do not react directly ie., the oxidation and reduction reactions take place separately at the anode and cathode respectively like H2 – O2 fuel cell. Other fuel cell like propane –O2 and methane O2 have also been developed.
H2 – O2 fuel cell
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