A galvanic cell is built at 298 K using the following half-cells: • Half-cell 1: 1.0…

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

Problem

A galvanic cell is built at 298 K using the following half-cells: • Half-cell 1: 1.0 M

\text{Fe}^{3+}

and 1.0 M

\text{Fe}^{2+}

in an inert platinum electrode system • Half-cell 2: 1.0 M

\text{Sn}^{4+}

and 1.0 M

\text{Sn}^{2+}

in an inert platinum electrode system The two compartments are connected by a salt bridge that contains 1.0 M

\text{KCl}

. The balanced overall reaction is

2\,\text{Fe}^{3+}(aq)+\text{Sn}^{2+}(aq)\rightarrow 2\,\text{Fe}^{2+}(aq)+\text{Sn}^{4+}(aq)

Assume the volume of solution in each half-cell is

100\,\text{mL}

and remains constant. (a) Identify the anode and the cathode for this galvanic cell. Support your answer with appropriate standard reduction potential data. (b) Write the half-reactions occurring at the anode and the cathode. (c) Specify which salt-bridge ion (

\text{K}^{+}

\text{Cl}^{-}

) migrates into each half-cell while the cell operates. Explain how this migration preserves charge balance. (d) A total charge of

0.193\,\text{C}

passes through the circuit. Calculate the number of moles of

\text{Fe}^{3+}

that are reduced during this time. (e) Using your answer to part (d), determine the new molarity of

\text{Fe}^{3+}

in the iron half-cell, assuming the solution volume stays at

100\,\text{mL}

and no volume change occurs due to ion migration.

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