Fuel cells
Fig. Lead storage battery
Fig. Nickel-Cadmium cell o It is used extensively in automobiles and invertors. o
The lead cell contains a lead anode and a lead dioxide( PbO2) cathode and sulphuric acid is used as an electrolyte. Anode: Pb( s) + SO4 2 –( aq)-- > PbSO4( s) + 2e – Cathode: PbO2( s) + SO4 2 –( aq) + 4H +( aq) + 2e –-- > PbSO4( s) + 2H2O( l)
o The net cell reaction is: Pb( s)+ PbO2( s)+ 2H2SO4( aq)-- > 2PbSO4( s) + 2H2O( l)
o While charging, the reaction within the battery is reversed and PbSO4( s) on anode and cathode is converted into Pb and PbO2, respectively. o
It has a longer life than lead storage cell and it requires more expenses to
o The net reaction is: Cd( s)+ 2Ni( OH) 3( s)-- > CdO( s) + 2Ni( OH) 2( s) + H2O( l)
Fuel cells
o
In this kind of cell the chemical energyof fossil fuels like coal, gas or oil is initially used to convertwater into high pressure steam and is used to run a turbine to generate