Question

Calculate ΔG∘rxn and E∘cell for a redox reaction with n = 3 that has an equilibrium constant of K = 5.3×10⁻².

ΔG∘rxn =

E∘cell =

Answer 1

We have relation, G ⁰_rxn = - 2.303 R T log K , where K is equilibrium constant.

G ⁰_rxn = - 2.303 8.314 J K ^-1 mol ^-1 298 K log  5.3 10 ⁻²

= + 72279 J / mol

= + 7.279 k J / mol

ANSWER : G ⁰_rxn = 7.3 k J / mol

We have relation , G ⁰ = - n F  E ⁰ cell

Where n = no. of moles of electrons transferred in the overall reaction.

We have, n = 3 , F = 96487 C / mol &   G ⁰ =7.279 k J / mol

72279 J / mol = - 3 96487 C / mol   E ⁰ cell  

E ⁰ cell = 72279 / ( - 3 96487 )

E ⁰ cell = - 0.2497 V

ANSWER :  E ⁰ cell = - 0.25 V