Bedlasky - 26-6-2021 at 20:32
Hi.
I often work with silver electrode amalgamated in mercury. It is used in chelatometry instead of ISE electrodes. This electrode can be used for
determination of quite wide range of metals, which is big advantage over ISE.
So I was wonder how this electrode works. I found several documents on this topic, these two are the most useful:
https://www.tau.ac.il/~advanal/PotentiometricTitrations.htm
https://www.google.com/url?sa=t&source=web&rct=j&...
Electrode works because of presence Hg/[Hg(edta)]2- redox couple. For this reason small amount of mercury EDTA must be added before titration - at
least according to documents.
But I never added mercury EDTA before titration. I just used freshly amalgated electrode without mercury EDTA and it work just fine. But I don't know
why it work. In theory without mercury EDTA electrode shouldn't take potential change in equivalence point. Can some explain this behavior?