A fuel cell can operate at very high temperatures, meaning the heat produced can be used to provide additional power ("Combined-Cycle", not CHP). If the overall HHV reaction is 1 H +50 H0 2 find the maximum efficiency of this fuel cell at STP by Entropy approach and Gibbs Free Energy approach. TABLE 9.4 Enthalpy of Formation H, Absolute Entropy S, and Gibbs Free Energy G at 1 atm, 25C for Selected Substances Substance State gas gas H H O 0 HO HO C CH CO CO CHOH gas gas liquid gas solid gas gas gas liquid H (kJ/mol) 217.9 0 247.5 0 -285.8 -241.8 0 -74.9 -110.5 -393.5 -238.7 S (KJ/mol K) 0.114 0.130 0.161 0.205 0.0699 0.1888 0.006 0.186 0.197 0.213 0.1268 G (kJ/mol) 203.3 0 231.8 0 -237.2 -228.6 0 -50.8 -137.2 -394.4 -166.4