If standard reduction potential (E^0) of ( Al ⁺³_ (aq) | Al _ (s) ) , ( Fe ⁺²_ (aq) | Fe _ (s) ) , ( Cu ⁺²_ (aq) | Cu _ (s) ) and ( Ag ⁺¹_ (aq) | Ag _ (s) ) are -1 66 V, -0 44 V, +0 34 V and +0 79 V respectively. Which of the following reaction is non spontaneous ?

Step-by-step solution

For a reaction to be non-spontaneous, the standard cell potential E⁰_ cell must be negative, where E⁰_ cell = E⁰_ cathode - E⁰_ anode . For the reaction 2 Ag _ (s) + Fe ⁺²_ (aq) 2 Ag ⁺¹_ (aq) + Fe _ (s) : Ag undergoes oxidation (anode) and Fe ⁺² undergoes reduction (cathode). E⁰_ cell = E⁰_ Fe ⁺²/ Fe - E⁰_ Ag ⁺/ Ag E⁰_ cell = -0.44 - 0.79 = -1.23 V Since E⁰_ cell For the other reactions, E⁰_ cell is positive, making them spontaneous: 2 Al _ (s) + 3 Cu ⁺²_ (aq) 2 Al ⁺³_ (aq) + 3 Cu _ (s) E⁰_ cell = 0.34 - (-1.66) =