Question

What is electrode potential? Give the factors which affect the electrode potential of a metal.

Hint:

At standard conditions ($[\,] = 1$ M, $p=1$ atm, $T=298$ K), $E=E^\circ$. Any deviation in concentration, temperature, or pressure shifts $E$ from $E^\circ$.

Answer 1

Definition:
Electrode potential is the potential difference developed between a metal electrode and the solution of its ions when the electrode is in equilibrium with those ions.
It expresses the tendency of the electrode to lose or gain electrons.
Factors affecting electrode potential:
1.\; Nature of the metal: Different metals have different intrinsic tendencies to be oxidized or reduced.
2.\; Ion concentration: Electrode potential varies with the concentration (activity) of metal ions according to the Nernst equation.
3.\; Temperature: Change in temperature alters activities of species and hence the potential.
4.\; Pressure of gas (for gas electrodes): For electrodes like SHE, the gas pressure affects the potential.
Nernst relation (298 K, base-10):
\[ E = E^\circ - \frac{0.0591}{n}\log\!\left(\frac{[Ox]}{[Red]}\right) \] This shows explicitly how concentration and $n$ influence $E$.