= 8. A fuel cell based on an oxygen ion conductor is held under open circuit conditions (no current is drawn) and is sup

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8 A Fuel Cell Based On An Oxygen Ion Conductor Is Held Under Open Circuit Conditions No Current Is Drawn And Is Sup 1 (149 KiB) Viewed 75 times

= 8. A fuel cell based on an oxygen ion conductor is held under open circuit conditions (no current is drawn) and is supplied with oxygen at the cathode (x =0), of oxygen partial pressure pO2(0) and a mixture of steam and hydrogen at the anode (x = L), with equivalent oxygen partial pressure of pO2(L). (a) Making use of the notion of local electrochemical equilibrium at the electrodes and global electrochemical equilibrium of the mobile oxygen ions, show that the Nernst potential is given by RT pO2(L) EN - In 4F pO2(0) (b) The value of the oxygen partial pressure at the anode can be determined from the known steam and hydrogen partial pressures supplied to the anode. Show that the Nernst potential can thus also be expressed as AyxGº RT PH2O(L) EN where is the standard Gibbs energy of reaction between 2F 2F po2 (OpH, (L)) oxygen and hydrogen to yield one mole of H2O. + In