Why is the reaction between Cu2+ and I- feasible? Watch
We are currently doing electrochemistry in A2 Chemistry.
We learnt that the E value for the reaction
Cu2+ (aq) + 2I- (aq) --> CuI (s) + 1/2 I2 (aq) is negative so the reaction is not supposed to be feasible. However, the reaction actually occurs and we were explained that this is because the precipitation of CuI removes Cu+ ions from the solution and so the equilibrium
Cu2+ (aq) + e- ⇌ Cu+ (aq) +0.15V
shifts to the right, making the E value more positive than that of
1/2 I2 (s) + e- ⇌ I- (aq) +0.54V
However, this does not make sense to me because the precipitation of CuI also removes I- ions from the solution and so the iodine equilibrium also shifts to the right, making its E value more positive as well. Furthermore, the overall reaction produces I2 as well which adds to the concentration of I2 and so the iodine equilibrium further shifts to the right (and so E value becoming more positive again)? So I thought the overall E value for the reaction would stay negative.
Can anyone explain to me why this reaction is really feasible?