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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: HgWonder on September 07, 2008, 03:59:12 PM

Title: electric potentials... confused
Post by: HgWonder on September 07, 2008, 03:59:12 PM

I am trying to figure out the change in potential when you use a 0.1M solution of KCl instead of a saturated (3.5M) KCl solution in a Calomel electrode.

Pt|Hg|Hg₂Cl₂|KCl  [0.242V vs NHE]

I applied the Nernst Equation but I wasn't sure if I was calculating this difference properly.  Thanks.   

Title: Re: electric potentials... confused
Post by: Borek on September 07, 2008, 04:33:03 PM

Show the equation you are using.

Title: Re: electric potentials... confused
Post by: HgWonder on September 07, 2008, 04:53:10 PM

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fmath%2F8%2Fc%2F1%2F8c13b8b34da2bb8e65841defe14aa185.png&hash=1a0714b957d868f864bc46396f925ffbd4284993)

Red= 3.5
Ox= 0.1
E^o= 0.242
R= 8.314472
T= 298.15
z= 1
F= 96485.309

Title: Re: electric potentials... confused
Post by: Borek on September 07, 2008, 05:37:07 PM

No, that's wrong. First of all - what is electrode reaction? Second - what is Hg₂²⁺ concentration? How does it depend on [Cl^-]?