Standard reduction potentials Knowledge-Based Download PDF

Questions

1. 1.

   In a standard galvanic cell, an unknown metal electrode $\text{X}(s)$ in a $1.0\text{ M }\text{X}^{2+}(aq)$ solution is coupled with a standard hydrogen electrode. If electrons spontaneously travel through the external circuit from the $\text{X}(s)$ electrode to the standard hydrogen electrode and produce a cell potential of $0.44\text{ V}$, what is the standard reduction potential of the $\text{X}^{2+}(aq)/\text{X}(s)$ half-reaction?

   • A) $+0.44\text{ V}$
   • B) $+0.22\text{ V}$
   • C) $-0.44\text{ V}$
   • D) $-0.22\text{ V}$
2. 2.

   Given the standard reduction potentials at 25 °C: $\text{Cl}_2(g) + 2e^- \rightarrow 2\text{Cl}^-(aq) \quad E^\circ = +1.36\text{ V}$ $\text{Br}_2(l) + 2e^- \rightarrow 2\text{Br}^-(aq) \quad E^\circ = +1.07\text{ V}$ $\text{Fe}^{3+}(aq) + e^- \rightarrow \text{Fe}^{2+}(aq) \quad E^\circ = +0.77\text{ V}$ $\text{I}_2(s) + 2e^- \rightarrow 2\text{I}^-(aq) \quad E^\circ = +0.54\text{ V}$ Which species can oxidize $\text{I}^-(aq)$ to $\text{I}_2(s)$ but cannot oxidize $\text{Br}^-(aq)$ to $\text{Br}_2(l)$ under standard conditions?

   • A) $\text{Fe}^{3+}(aq)$
   • B) $\text{Cl}_2(g)$
   • C) $\text{Br}^-(aq)$
   • D) $\text{Fe}^{2+}(aq)$
3. 3.

   Given the standard reduction potentials at 25 °C: $\text{Ni}^{2+}(aq) + 2e^- \rightarrow \text{Ni}(s) \quad E^\circ = -0.26\text{ V}$ $\text{Cu}^{2+}(aq) + 2e^- \rightarrow \text{Cu}(s) \quad E^\circ = +0.34\text{ V}$ $\text{Ag}^+(aq) + e^- \rightarrow \text{Ag}(s) \quad E^\circ = +0.80\text{ V}$ $\text{Au}^{3+}(aq) + 3e^- \rightarrow \text{Au}(s) \quad E^\circ = +1.50\text{ V}$ Which metal will spontaneously react with $\text{H}^+(aq)$ to produce $\text{H}_2(g)$ under standard conditions?

   • A) $\text{Ni}(s)$
   • B) $\text{Cu}(s)$
   • C) $\text{Ag}(s)$
   • D) $\text{Au}(s)$
4. 4.

   Given the standard reduction potentials $\text{Cr}^{3+}(aq) + 3e^- \rightarrow \text{Cr}(s)$ with $E^\circ = -0.74\text{ V}$ and $\text{Cd}^{2+}(aq) + 2e^- \rightarrow \text{Cd}(s)$ with $E^\circ = -0.40\text{ V}$, what is the standard cell potential ($E^\circ_{\text{cell}}$) for the spontaneous reaction in a galvanic cell constructed from these two electrodes?

   • A) -1.14 V
   • B) +1.14 V
   • C) +0.34 V
   • D) -0.34 V
5. 5.

   Given the standard reduction potentials at 25 °C: $\text{Fe}^{3+}(aq) + e^- \rightarrow \text{Fe}^{2+}(aq) \quad E^\circ = +0.77\text{ V}$ $\text{I}_2(s) + 2e^- \rightarrow 2\text{I}^-(aq) \quad E^\circ = +0.54\text{ V}$ $\text{Sn}^{4+}(aq) + 2e^- \rightarrow \text{Sn}^{2+}(aq) \quad E^\circ = +0.15\text{ V}$ Which species is the strongest reducing agent under standard conditions?

   • A) $\text{Sn}^{2+}(aq)$
   • B) $\text{Fe}^{2+}(aq)$
   • C) $\text{I}^-(aq)$
   • D) $\text{Fe}^{3+}(aq)$