Two galvanic cells, Cell X and Cell Y

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

Problem

Two galvanic cells, Cell X and Cell Y, are constructed at 298 K using zinc and copper electrodes separated by a salt bridge. The relevant standard reduction potentials are:

\mathrm{Zn^{2+}}+2e^-\longrightarrow \mathrm{Zn}\;(E^{\circ}=-0.76\,\text{V})

\mathrm{Cu^{2+}}+2e^-\longrightarrow \mathrm{Cu}\;(E^{\circ}=+0.34\,\text{V})

The left-hand electrode is zinc metal in aqueous

\mathrm{Zn^{2+}}

; the right-hand electrode is copper metal in aqueous

\mathrm{Cu^{2+}}

. • Cell X

[\mathrm{Zn^{2+}}]=0.0050\,\text{M}

[\mathrm{Cu^{2+}}]=1.00\,\text{M}

• Cell Y

[\mathrm{Zn^{2+}}]=1.00\,\text{M}

[\mathrm{Cu^{2+}}]=0.0050\,\text{M}

Assume all gases (if any) are at 1.00 atm and that temperature remains constant at 298 K throughout the experiment. (a) Write the balanced overall cell reaction that occurs spontaneously in each cell. (b) For Cell X, calculate the reaction quotient

Q

using the given concentrations. (c) Using the result from part (b), determine the cell potential

E_{\text{X}}

for Cell X at 298 K. Express your answer in volts with three significant figures. (d) Repeat parts (b) and (c) for Cell Y to obtain

Q

and

E_{\text{Y}}

. (e) Rank

E_{\text{X}}

E_{\text{Y}}

, and the standard cell potential

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

from largest to smallest magnitude. Briefly justify the ranking based on the numerical values of the reaction quotients.

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