Suppose that a hydrogen fuel cell, as described in the text, is to be operated at 75° C and atmospheric pressure. We wish to estimate the maximum electrical work done by the cell, only the...

Suppose that a hydrogen fuel cell, as described in the text, is to be operated at 75° C and atmospheric pressure. We wish to estimate the maximum electrical work done by the cell, only the room-temperature data at the back of this book. It is convenient to first establish a zero-point for each of the three substances,H₂
, O₂, and H₂O. Let us take G for both H₂
and O₂
to be zero at 25°C, so that G for a mole of H20 is -237 kJ at 25°C.
(a) Using these conventions, estimate the Gibbs free energy of a mole of H₂
at 75°C. Repeat for O₂
and H₂O.
(b) Using the results of part (a), calculate the maximum electrical work done by the cell at 75°C, for one mole of hydrogen fuel. Compare to the ideal performance of the cell at 25°C.