3. a) If a fuel cell has a reversible voltage of E1 at P=P1 and T=T1, determine an expression for temperature T2 that would be required to maintain the cell voltage at E1 if the cell pressure is adjusted to P2. Consider the general reaction R (reactants) P (products). Use x for mole fraction and note that, for any species i, its partial pressure Pi=xiP (assuming ideality). The change in the number of moles of gas nG=vPvR where vP and vR are the number of moles of product and reactant gases, respectively. Now simplify for a H2/O2 fuel cell producing liquid water (xH2=xO2=1). b) For this H2/O2 fuel cell operating at room temperature and atmospheric pressure using pure oxygen, what temperature would be required to maintain the original reversible voltage if the operating pressure is reduced by an order of magnitude? R=8.314Jmol1K1. Hints a) For the general reaction R (reactants) P (products) E=ETnFRTln(PoP)vR(PoP)vPRPxivixivi where vi= number of moles of component i and PO= reference pressure (could just be omitted as eventually assume PO=1atm ). For ET use the solution to problem 1 . For the voltages to be equal, E(T1,P1)=E(T2,P2). Solve for T2