A student investigates a galvanic cell that combines metallic iron with a silver electrode

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

Problem

A student investigates a galvanic cell that combines metallic iron with a silver electrode. Relevant half-reactions measured at 298 K are provided below.

Fe(s) \to Fe^{2+}(aq) + 2\,e^{-}

(

E^\circ = +0.44\,\text{V}

, quoted as an oxidation potential)

Ag^{+}(aq) + e^{-} \to Ag(s)

(

E^\circ = +0.80\,\text{V}

, reduction potential) Standard 1.0 M solutions of

Fe^{2+}(aq)

and

Ag^{+}(aq)

are used, and all gases are at 1 bar. (a) Express the iron half-reaction as a reduction process and state its standard reduction potential. (b) Write the balanced overall redox equation for the spontaneous reaction in the cell, including physical states. (c) Calculate the standard cell potential,

E^\circ_{\text{cell}}

, for the reaction written in part (b). (d) Using

n = 2\,\text{mol}\,e^{-}

and

F = 96\,485\,\text{C\,mol}^{-1}

, determine the standard free-energy change,

\Delta G^\circ

, in kJ for the cell reaction. Interpret the sign of

\Delta G^\circ

in terms of thermodynamic favorability.

Related theory

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