Faradays Laws Consumption and Production of Species

If the voltage is the fuel cell voltage, the output is the electrical power from the fuel cell. If instead the voltage in Eq. (2.23) is the voltage potential lost due to resistance, the power generated is thermal dissipation. The delineation between electrical power and heat dissipation rate will become clear in fnture chapters if it is not now. Thus, electrical power has units of watts (J/s), as expected. Ohm s law can also be substituted into Eq. (2.17) to obtain alternate expressions for electrical power  

Since it is often the case that mechanical and electrical systems operate in conjunction with one another, it is imperative to be able to convert among the units used for electrical systems and thermo-mechanical systems. 

Example 2.1 Simple Electrical Calculations A given circuit has a continuous 5 A DC (direct current) and an overall resistance of 10 S2. Calculate 

COMMENT The resistance shown represents the resistance in a generic electric circuit not a fuel cell. 

In this section we consider a fundamentally important question How much mass of a given reactant is required to produce a given amount of current Conversely, how much current is required to produce a certain amount of product Clearly, the fundamental relationships should be based on conservation of mass and charge. We cannot produce mass from an electrochemical reaction, only rearrange it, and a given amount of reactant can produce a fixed number of charged species, based on the balanced chemical reaction. Consider 1 mol 

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