
123Thermodynamics of Fuel Cells
dG = VdP − SdT. (3.44d)
For an isothermal process, the change in the Gibbs function expression
reduces to
dG = VdP. (4.36)
Now, considering the ideal gas equation of state and substituting V
nRT
=
into Equation 4.36, we get
d
d
GnRT
P
= . (4.37)
TABLE 4.3
Thermodynamic Data of Hydrogen-Oxygen Fuel Cell over a Range of Temperature
Temp (K) Temp (C)
Enthalpy of
Reaction,
kJ/mol
Entropy of
Reaction,
J/mol.K
Gibbs Energy
of Reaction,
J/mol Voltage (V)
273 0 −286.6225 −166.1743 −241260 1.2513
283 10 −286.3007 −164.9659 −239620 1.2428
293 20 −285.9788 −163.8298 −237980 1.2343
298 25 −285.8185 −163.2828 −237160 1.2301
303 30 −285.6587 ...