For H2(g) + 1/2 O2(g) -> H2O(l), Delta_r G deg = -237 kJ mol^-1 and Delta_r H deg = -286 kJ mol^-1. The maximum thermodynamic efficiency of a hydrogen-oxygen fuel cell is about

JEE Main levelSingle correct optionDifficulty 2 of 3ec12

For $H X_{2} (g) + \frac{1}{2} O X_{2} (g) H X_{2} O (l)$ , $Δ_{r} G^{\circ} = - 237 kJ mo l^{- 1}$ and $Δ_{r} H^{\circ} = - 286 kJ mo l^{- 1}$ . The maximum thermodynamic efficiency of a hydrogen-oxygen fuel cell is about

Efficiency

= \frac{Δ G ^{\circ}}{Δ H ^{\circ}} = \frac{237}{286} = 0.83

. The remaining 17% appears as

T Δ S

, released as heat even in an ideal cell.