1) What are the distinguishing features between primary cells secondary cells, fuel cells and solar cells?
2) The lead acid battery ( a secondary cell ) can be recharged and reused for a few years after which it can not be recharged and reused. Can you think of reason why it can not be used any further ?
3) Propane (C3H8 ) can be used in a fuel cell and the combustion products are CO2 and H2O. Write a balanced chemical reaction for the combustion process. The standard free energy of combustion is -2108 kJ/mol of C3H8. Since five oxygen molecules (oxidation state zero) are reduced to the oxidation state of -2 , 20 electrons are involved in the process (O2 + 4 H+ + 4e- 2H2O) What is the emf of the fuel cell ?
4) The standard free energies of combustion of CH4 and CH3OH are - 818 and -706.9 kJ/mol respectively. Calculate the emfs of these cells. The standard molar enthalpies for the combustion reactions are -890.4 and - 7640 kJ / mol. Defining the relative efficiencies of electrical vs thermal processes as
E = Gom / Hom. Calculate the values of E for CH4 and CH3OH
5) For a few common semiconductors, find out the excitation energy required to excite the electrons / holes so that they can conduct electricity.
6) Contrast the natural photosynthetic process with that of the processes occurring in a fuel cell and a solar cell.
2H2O) What is the emf of the fuel cell ? 
Gom / 
Hom. Calculate the values of E for CH4 and CH3OH 
