For a cell reaction with $n = 2$ , $Δ_{r} H^{\circ} = - 220.0 kJ mo l^{- 1}$ and $Δ_{r} S^{\circ} = - 40.0 J K^{- 1} mo l^{- 1}$ , both assumed independent of temperature. The standard EMF of the cell at 350 K (in V, two decimals) is ( $F = 96500 C mo l^{- 1}$ ).

Numerical answer type, answer in V, tolerance 0.01.

Answer: 1.07 V

First find

Δ_{r} G^{\circ}

at 350 K:

Δ_{r} G^{\circ} = Δ_{r} H^{\circ} - T Δ_{r} S^{\circ} = - 220000 - 350 \times (- 40.0) = - 220000 + 14000 = - 206000 J mo l^{- 1}

. Then

E^{\circ} = - Δ_{r} G^{\circ} / (n F) = 206000/ (2 \times 96500) = 1.067 V \approx 1.07 V

. Using

Δ_{r} H^{\circ}

alone would give

1.14 V

, which ignores the entropy term.