13.15 cell diagram

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Kayla Denton 1A
Posts: 106
Joined: Fri Sep 26, 2014 2:02 pm

13.15 cell diagram

Postby Kayla Denton 1A » Sat Feb 07, 2015 10:23 am

Hi! I have a few questions about 13.15 d.
The anode reaction is Cd + 2OH- --> Cd(OH)2 + 2e-
The cathode reaction is 2Ni(OH)3 + 2e- --> 2Ni(OH)2 + 2OH-

In the cell diagram, I understand why they have a Cd(s) electrode, but why do they have an Ni(s) electrode when Ni itself doesn't take part in the reaction?
Second, where did potassium come from? They've written KOH.
Third, if why is OH only written on the anode side and not the cathode (when it is present in both)?

Thanks!

Regina Chi 2K
Posts: 51
Joined: Fri Sep 26, 2014 2:02 pm

Re: 13.15 cell diagram

Postby Regina Chi 2K » Sat Feb 07, 2015 1:03 pm

Is the Ni (s) electrode present because both species are either aqueous or gas? They just picked Ni (s) for convenience since part of the reaction deals with nickel ions. And for the KOH, I went to office hours and the TA said that it would have been okay to just include OH- and that the K does not make too much of a difference as it would be just a dissolved ion in the aqueous solution. I'm not sure about the last part though... I hope this helped!

Niharika Reddy 1D
Posts: 127
Joined: Fri Sep 26, 2014 2:02 pm

Re: 13.15 cell diagram

Postby Niharika Reddy 1D » Sun Feb 08, 2015 3:01 pm

I was also wondering why the OH- was omitted from the cathode side when it is present in the reduction half reaction. If anyone has some insight as to why this is, it would be much appreciated! Thank you!

Justin Le 2I
Posts: 142
Joined: Fri Sep 26, 2014 2:02 pm

Re: 13.15 cell diagram

Postby Justin Le 2I » Sun Feb 08, 2015 10:26 pm

I think one of the reasons why these problems have so many different answers is that there are multiple answers to making cell diagrams. I would include the OH- on both sides just in case.


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