Fuel cells are the commercial cells which converts the chemical energy into electrical
Channel: Doubtnut
Date: 2020-04-19

Fuel cells are the commercial cells which converts the chemical energy into electrical energy and differ from the normal batteries since fuel cells require constant source of fuel and oxygen to obtain electric current. However, they can be used to produce electricity as long as the supply of fuel and oxygen is maintained. All fuel cells consist of an andoe and a cathode and an electrolyte which allows charges to move between the two sidez of the fuel cell. Electrons are drawn from anode to cathode through an external circuit and hence produce direct current electricity.  Under practical cases, efficient of fuel cell is around `40-60%` and in some cases it may be as high as `85-90%`   Some common examples of fuel cell are diect methanol fule cell (DMFC), Direct Borohydride fuel cell (DBFC), alkaline fuel cell (AFC) and others.While in DMFC the electrolyte is an ionomer (proton exchange monomer) in case of AFC and DBFC the electrolyte is an aqueous alkaline solution. Also, in case of DBFC the borohydride gets oxidised to metaborate, In all the above three cases, at cathode reduction of `O_(2)`(gas) occurs in a medium controlled by the electrolyte. Based on this information answer the electrolyte. Based on the information answer the question that follow :   Data   `{:(DeltaH_(f)^(@)CH_(3)OH(l)=-230kJ//"mole",,DeltaH_(f)^(@)CO_(2)`=-390kJ//"mole"),(Delta_(f)^(@)H_(2)O(l) = - 285 kJ//"mole",,S_(mH_(2)O(l))^(@)=130J//K "mole"),(S_(mCO_(2(g))) = 210 J//K "mole",S_(mH_(2)O(l))^(@) = 110 J//K "mol"),(S_(mO_(2(g)))=206J//K "mole",,S_(mH_(2(g))) = 130J//K "mole"),("All data at" 300 K.,1/F = 10^(-5)C^(-1)):}`   If in DBFC it is known that sodium borohydride is taken as a fuel than which of the following reaction wil be occuring at approprite electrode in the DBFC ?