Two half-cells are available to a technician: 1

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

Problem

Two half-cells are available to a technician: 1. A silver electrode in

1.0\,\text{M}\,Ag^+(aq)

2. A nickel electrode in

1.0\,\text{M}\,Ni^{2+}(aq)

Selected standard reduction potentials (25

^{\circ}\text{C}

Ag^+(aq) + e^- \rightarrow Ag(s)

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

Ni^{2+}(aq) + 2\,e^- \rightarrow Ni(s)

E^\circ = -0.25\,\text{V}

Faraday constant:

F = 9.65 \times 10^4\,\text{C mol}^{-1}

(a) Write the balanced overall reaction that occurs when the two half-cells are connected to operate spontaneously as a galvanic cell. (b) Calculate the standard cell potential,

E^\circ_{\text{cell}}

, for the galvanic cell. (c) Determine the value of

\Delta G^\circ

(in kJ mol

^{-1}

of reaction as written in part (a)) for the spontaneous process. (d) The technician now wishes to plate exactly

2.50\,\text{g}

of silver metal onto the silver electrode by running the cell in electrolytic mode at

70\,\%

electrical efficiency. Calculate the minimum charge that must pass through the circuit and the minimum external potential that must be applied under these conditions.

Related theory

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