1.

Explain the function of H_(2)-O_(2) fuel cell.

Answer»

Solution :Fuel cell :
(i) The galvanic cell in which the energy of combustion of fuels is directly converted into electrical energy is called the fuel cell.
(ii) It requires a continuous supply of reactant to keep functioning.
(iii) The general representation of a fuel cell is follows
Fuel | Electrode | Electrolyte | Electrode | Oxidant
(iv) Let us understand the function of fuel cell by considering hydrogen - oxygen fuel cell.
(v) 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.
(vi) Porous graphite electrode containing NI and NIO serves as the inert electrodes.
(vii) Hydrogen and oxygen gases are bubbled through the anode and cathode, respectively.
Oxidation OCCURS at the anode:
`2H_(2(g))+4OH_((AQ))^(-) rarr 4H_(2)O(L)+4e^(-)`
Reduction occurs at the cathode
`O_(2(g))+2H_(2)O(l)+4e^(-) rarr 4OH_((aq))^(-)`
The overall reaction is
`2H_(2(g))+O_(2(g)) rarr 2H_(2)O(l)`


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