What are the fuel cells ? How are they different from galvanic cells ? Give the construction of `H_(2), O_(2)` fuel cell ?

Explanation

A fuel cell is a galvanic cell in which the chenical energy of fuel-oxidant syste m is converted directly into electrical energy.
`to` Convertional Galvanic cell converts chemical energy into electrical energy by spontaneous redox reactions.
` to` Fuel cell convert energy of combustion of fuels like hydrogen, meghane etc., into electrical energy. These cause less pollution,.
`H_(2)-O_(2)` fuel cell: In this cell, hydrogen and oxygen are bubbled through porous carbon electrodes into Conc. NaOH solution. Electrodes are embedded with suitable catalysts. The electrode reactions are
`O_(2(g))+2H_(2)O_((l))overset(+4e^(-))to4OH_((aq))^(-)` (Cathode)
`2H_(2_((g)))+4OH_((aq))^(-) to4 H_(2)O_((l)) +4e^(-)` (anode)
Overall reaction : `2H_(2_(g))+O_(2_(g))to 2H_(2) O_((l))`
The cell function as long as the reacting gases are in supply. The hate of combustion is directly converted into electrical energy.