Answer to Question #29891 in Physical Chemistry for Branden

Question

Predict whether Fe3+ can oxidize I- to I 2 under standard-state conditions

Answer 1

The appropriate half-reactions are
I₂(s) + 2e^− → 2I^−(aq)
E_anode = 0.53V
Fe³⁺(aq) + e^− → Fe²⁺(aq)
E_cathode = 0.77 V
Since Fe³⁺/Fe²⁺ is more positive, it should oxidize I^– to I₂. This makes the I₂/I^– half-reaction the anode. The standard emf can be found
E_cell = E_cathode − E_anode = 0.77 V − 0.53 V = 0.24 V