A galvanic cell is assembled under standard conditions using a zinc electrode in a…

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

Problem

A galvanic cell is assembled under standard conditions using a zinc electrode in a

1.0\,\text{M}

\mathrm{Zn}^{2+}(\mathrm{aq})

solution and a copper electrode in a

1.0\,\text{M}

\mathrm{Cu}^{2+}(\mathrm{aq})

solution. The relevant standard reduction potentials are given below.

\mathrm{Zn}^{2+}(\mathrm{aq}) + 2\,e^- \rightarrow \mathrm{Zn}(\mathrm{s}) \quad E^\circ = -0.76\,\text{V}

\mathrm{Cu}^{2+}(\mathrm{aq}) + 2\,e^- \rightarrow \mathrm{Cu}(\mathrm{s}) \quad E^\circ = +0.34\,\text{V}

The Faraday constant is

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

. (a) Write the balanced overall reaction that occurs in the cell under standard conditions. (b) Determine the standard cell potential,

E^\circ_\text{cell}

, for the reaction identified in part (a). (c) State the value of

n

, the number of moles of electrons transferred in the balanced reaction, and calculate the standard Gibbs free energy change,

\Delta G^\circ

, in kJ for the overall reaction as written in part (a). (d) Explain how the calculated sign of

\Delta G^\circ

is consistent with the operation of the cell as a galvanic (voltaic) cell.