The following reactions may be made to operate in fuel cells at 298 K.

The following reactions may be made to operate in fuel cells at 298 K.

CH4(g) + 2O2(g) ⇄ CO2(g) + 2H2O(l)                                                                                                            

C2H6(g) + O2(g) ⇄ 2CO2(g) + 3H2O(l)                                                                                                      

C3H8(g) + 5O2(g) ⇄ 3CO2(g) + 4H2O(l)                                                                                                        

CH3OH(g) + O2(g) ⇄ CO2(g) + 2H2O(l)                                                                                                                

For each case, calculate:

(i)   the number of electrons transferred overall per mole cell reaction

(ii) the reversible electromotive force (e.m.f., voltage) of the cell at 298 K, and

(iii) the maximum efficiency of the cell.