Hi! Can anyone explain me how to calculate the activity of an oxidant/reductant? I have to calculate a silver/silver chloride electrode in physical chemistry.

Question

anonymous · Answer

$$E=E _{0}+\frac{ RT }{ zF }\ln \frac{ a _{ox} }{ a _{red} }$$
So I don't get how to derive a.

vincent-lyon.fr · Answer

In your case, the redox couple is $Ag^+/Ag$
Half equation is   $Ag^++e^- \rightarrow Ag_{(s)}$

Which leads to $E=E _{0}+\Large\frac{ RT }{ zF }\ln \Large \frac{ [Ag^+]}{ 1 }$

vincent-lyon.fr · Answer

In the presence of chloride ions, $[Ag^+]=K_S/[Cl^-]$
Bythe way $z=1$ here.
After substituting [Ag+], you will get a workable equation.