In Electrolysis, an Electric Current Is Used to Drive a Nonspontaneous Reaction

Unlike batteries, fuel cells do not store chemical energy. Reactants must be constantly resupplied, and products must be constantly removed from a fuel cell. In this respect, a fuel cell resembles an engine more than it does a battery. However, the fuel cell does not operate like a heat engine and therefore is not subject to the same kind of thermodynamic limitations in energy conversion. 

Properly designed fuel cells may be as much as 70 percent efficient, about twice as efficient as an internal 

In Electrolysis, an Electric Current Is Used to Drive a Nonspontaneous Reaction 

In contrast to spontaneous redox reactions, which result in the conversion of chemical energy into electric energy, electrolysis is the process in which electric energy is used to cause a nonspontaneous chemical reaction to occur. An electrolytic cell is an apparatus for carrying out electrolysis. The same principles underlie electrolysis and the processes that take place in galvanic cells. Here we will discuss three examples of electrolysis based on those principles electrolysis of molten NaCl, water, and aqueous NaCl. Then we will look at the quantitative aspects of electrolysis. 

Iron cathode Iron cathode Carbon anode (a) 

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