Why is the reaction between Cu2+ and I- feasible? Watch

C0balt
Badges: 14
Rep:
?
#1
Report Thread starter 4 years ago
#1
Hello,

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?

Thanks
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • The University of Law
    The Bar Series: Applications and Interviews - London Bloomsbury campus Postgraduate
    Thu, 17 Oct '19
  • Cardiff Metropolitan University
    Undergraduate Open Day - Llandaff Campus Undergraduate
    Sat, 19 Oct '19
  • Coventry University
    Undergraduate Open Day Undergraduate
    Sat, 19 Oct '19

Why wouldn't you turn to teachers if you were being bullied?

They might tell my parents (2)
10.53%
They might tell the bully (3)
15.79%
I don't think they'd understand (3)
15.79%
It might lead to more bullying (6)
31.58%
There's nothing they could do (5)
26.32%

Watched Threads

View All