A galvanic cell is constructed under standard conditions using the following two reduction… — JAMB UTME

A galvanic cell is constructed under standard conditions using the following two reduction half-reactions:

\text{Fe}^{3+}_{\text{(aq)}} + \text{e}^- \rightarrow \text{Fe}^{2+}_{\text{(aq)}}, \quad E^\circ = +0.77\text{ V}

\text{Sn}^{4+}_{\text{(aq)}} + 2\text{e}^- \rightarrow \text{Sn}^{2+}_{\text{(aq)}}, \quad E^\circ = +0.15\text{ V}

What is the standard cell potential ( $E^\circ_{\text{cell}}$ ) in volts for the spontaneous overall reaction?

Answer: 0.62 V

Answer

The standard cell potential for the spontaneous reaction is +0.62 V.

In a spontaneous galvanic cell, reduction takes place at the cathode, which is the electrode with the higher standard reduction potential (+0.77 V for

\text{Fe}^{3+}/\text{Fe}^{2+}

). Oxidation occurs at the anode (+0.15 V for

\text{Sn}^{4+}/\text{Sn}^{2+}

). Substituting these values into

E^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}}

yields

+0.77\text{ V} - (+0.15\text{ V}) = +0.62\text{ V}

Step-by-Step Solution

Identify the cathode and anode based on standard reduction potentials.

Cathode: Fe3+/Fe2+ half-cell (E° = +0.77 V); Anode: Sn4+/Sn2+ half-cell (E° = +0.15 V).

In a spontaneous galvanic cell, reduction occurs at the electrode with the more positive standard reduction potential.

Apply the standard electromotive force equation.

E°cell = E°cathode - E°anode = +0.77 V - (+0.15 V) = +0.62 V

The cell potential measures the overall potential difference between the reduction half-cell and oxidation half-cell.

Key Concept

Standard Cell Potential Calculation

Estimated Time:1m 30s

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