Chapter 20, Problem 4STP

Interpretation Introduction

Interpretation:

The standard potential is to be calculated out of the given cell representation.

Concept introduction:

Reduction will occur at that electrode having high reduction potential.

Answer to Problem 4STP

Correct answer:

Option A. $\text{Al}|{\text{Al}}^{\text{+3}}{\Vert \text{Hg}}^{\text{+2}}|\text{Hg}$ is correct.

Explanation of Solution

Reason for correct option:

The reduction potential of ${\text{Hg}}^{\text{2+}}|\text{Hg}$ electrode is more than that of ${\text{Al}}^{\text{3+}}|\text{Al}$. So, reduction will occur at the mercury electrode and oxidation will occur at the aluminum electrode.

The reduction potential of ${\text{Al}}^{\text{+3}}|\text{Al}\text{= -1}\text{.662}$ V

The reduction potential of ${\text{Hg}}^{\text{+2}}|\text{Hg}\text{=0}\text{.851}$ V

$\begin{array}{l}{\text{E°}}_{\text{cell}}{\text{=E°}}_{\left(\text{cathode}\right)}{\text{-E°}}_{\left(\text{anode}\right)}\\ \text{= 0}\text{.851- }\left(\text{-1}\text{.662}\right)\\ \text{= 2}\text{.513V}\end{array}$

The standard potential of a cell is $\text{2}\text{.513V}$

Conclusion

Reasons for incorrect options:

A. Not math with calculated value.

C. Not math with calculated value.

D. Not math with calculated value.