For this problem, we have to calculate for the ΔGf of I- when Ecell for the reaction is +0.74 V
Recall that ΔG can be calculated as:
In this case, we can calculate for the ΔGf of I- using the equation as:
Note that ΔGf for compounds in standard conditions are 0 (I2, H3O+ and O2)
To do so, we have to follow the steps:
Consider a galvanic cell that uses the reaction
4H3O+ (aq) + 4I- (aq) + O2 (g) → 2I2 (s) 6H2O (l).
If Ecell is +0.74 V, calculate ΔG°f of I- (aq) at 25 °C. Show all work and circle your final answer.
ΔG°f (H2O(l)) = -237.18 kJ/mol at 25 °C.
Anode: 4I-(aq) → 2I2(g) + 4e- ε°ox = =0.54 V
Cathode: O2(g) + 4H3O+(aq) + 4e- → 6H2O(l) ε°red = +1.23 V
Overall rx: 4H3O+(aq) + 4I-(aq) + O2(g) → 2I2(s) + 6H2O(l) ε°cell = 0.69 V