"Even combustion of fuels can be used to generate electricity". Comment on this statement by taking the reactions involved in `H_2-O_2` fuel cell.

Explanation

Ans: Fuel cells are galvanic cells in which chemical energy.of combustion of a fuél is converted into electrical energy. Such a.cell converts `74 %` of chemical energy into electrical energy. The fuel `(H_2, CH_4, C O.` etc.) used in the gaseous state. `H_2-O_z` cell is a common example. In this cells hydrogen and oxygen are bubbled from outer compartment through `A` porous carbon electrode into conc. `NaOH` solution takén in the central compartment. Here, hydrogen gets oxidiżed and oxygen gets reduced. The reactions are:
At anode `: 2[H_2+2 OH_z 2 H_2 O+2 overlinee]`
At cathode : `O_2+2 H_2 O+4 e-4 OH`
Overall reaction : `2 H_2+O_2 2 H_2 O`
Thus gaseous materials are consumed and the cells works continuouisly.as long as `H_2` and `O_2` are supplied. Fuel cells are more efficient than conventional "inethods of generatingenergy.