Question

A) How much power is generated by a fuel cell that is fed 1.050 moles of H2 per hour with a stoichiometric rate of O2?

the answer is not 132 nor 138.5

B) If   750   W was required to power a device, how many moles of H₂ would be required to be fed per hour (assuming O₂ is fed at a stoichiometric ratio)?

Answer 1

To do this, I need the whole reaction, because I have no information of the reaction that is taking place, however I can give you guidance to solve this.

First you need to calculate the standard potential of the cell, if the reaction is with H2 and O2, then the potential would be:
E° = 0.43 + 0.83 = 1.23 V

This assuming the reaction will generate water.

With this, calculate the free energy DG° = -nFE°

When you calculate that (Once again I need the whole reaction so I can know the exact number of electrons transfered in the reaction). And F = 96500.

With this value, multiply this value by the moles/h of H2, and then convert hours to second. That will give you the power.

To get the energy, just use the expression E = P * t

Hope this helps