[oneat]

Will I get oxygen or Silver cation electrolysing water with silver cathode?

[DevaDevil]

reduction:

2H⁺ + 2 e^---> H₂ (g); E⁰ = 0V

Oxidation possibilities:

2 H₂O -->  4 H⁺ + 4 e^- + O₂ (g);  E⁰ = -1.23V
ro
2Ag(s) + H₂O --> Ag₂O + 2 H⁺ + 2 e^-;  E⁰ = -1.17V (partial oxidation of silver)
or
Ag (s) --> Ag⁺ + e^-; E⁰ = -0.80V (full 1-valent oxidation of silver)


which one of the oxidation reactions costs the least energy based on the NERNST equation? This is the one that will happen in electrolysis.

[Borek]

which one of the oxidation reactions costs the least energy based on the NERNST equation? This is the one that will happen in electrolysis.

Unless it will be disfavored for kinetic reasons.

[DevaDevil]

agreed, same goes if indeed the silver-oxide (or hydroxide) layer is formed to cover the electrode.

I just point to the way on how to predict if dissolution might happen