Question

For given half cell; $A{l}^{+3}+3e^{-}\to Al$; on increasing $\left[A{l}^{+3}\right]$, the electrode potential:

• A. Increases
• B. Decreases
• C. No change
• D. First increases then decreases

Answer 1

The correct option is A Increases

$A{l}^{3+}+3e^{-}⟶Al$

We know that electrode potential at any concentration is

$E=E^o-\frac{0.059}{n}\log K_C$

where n is the number of electrons and $E_o$ is the standard electrode potential.

$A{l}^{3+}+3e^{-}⟶Al$

$K_C=\frac{1}{\left[{Al}^{3+}\right]}⟶$ for the given reaction.

$E=E^o-\frac{0.059}{n}\log \left(\frac{1}{\left[{Al}^{3+}\right]}\right)=E^o+\frac{0.059}{n}\log \left(\left[{Al}^{3+}\right]\right)$

So, from the above equations, on increasing $\left[A{l}^{3+}\right]$, the electrode potential increases.