A battery developer is investigating the possible use of metal M (with two accessible…

CHEMISTRY · Multi-part · A Level · Chemistry · Electrode potentials · Electrode potentials

Problem

A battery developer is investigating the possible use of metal M (with two accessible oxidation states M

^{2+}

and M

^{3+}

) in combination with three candidate metal electrodes A, B, and C. The relevant standard reduction potentials are provided below.

Half-Reaction	$E^{\circ}_{\text{red}}$ (V)
$\text{M}^{3+}+e^− \rightarrow \text{M}^{2+}$	$+0.16$
$\text{A}^{3+}+3e^− \rightarrow \text{A}$	$−0.50$
$\text{B}^{2+}+2e^− \rightarrow \text{B}$	$−0.25$
$\text{C}^+ + e^− \rightarrow \text{C}$	$+0.80$

(a) Construct every distinct galvanic cell that can be formed by coupling one half-reaction involving M with one half-reaction involving A, B, or C. For each cell, write the balanced overall equation and compute

E^{\circ}_{\text{cell}}

. (b) Using the results from part (a), determine which cell would deliver the largest magnitude of standard free energy change,

|\Delta G^{\circ}|

, per mole of electrons transferred. Show the reasoning that leads from

E^{\circ}_{\text{cell}}

to your conclusion. (c) Suppose a design constraint limits the battery to reactions that transfer no more than two moles of electrons per formula unit of reactant consumed. Re-evaluate your rankings from part (a) under this new constraint and identify the optimal cell. Justify your selection quantitatively. (d) Propose one chemical or materials-based strategy (other than changing temperature) that could further increase the operational cell potential of the chosen battery. Provide a brief explanation grounded in electrochemical principles.

Related theory

Browse the problem library