This question is about vanadium compounds and ions.
Use data from the table below to identify the species that can be used to reduce VO2+\text{VO}^{2+}VO2+ ions to V3+\text{V}^{3+}V3+ in aqueous solution and no further. Explain your answer.
| Electrode half-equation | Eθ / VE^\theta \text{ / V}Eθ / V |
|---|---|
| VO2+(aq)+2H+(aq)+e−→V3+(aq)+H2O(l)\text{VO}^{2+}(\text{aq}) + 2\text{H}^+(\text{aq}) + e^- \to \text{V}^{3+}(\text{aq}) + \text{H}_2\text{O}(\text{l})VO2+(aq)+2H+(aq)+e−→V3+(aq)+H2O(l) | +0.34+0.34+0.34 |
| V3+(aq)+e−→V2+(aq)\text{V}^{3+}(\text{aq}) + e^- \to \text{V}^{2+}(\text{aq})V3+(aq)+e−→V2+(aq) | −0.26-0.26−0.26 |
| Fe3+(aq)+e−→Fe2+(aq)\text{Fe}^{3+}(\text{aq}) + e^- \to \text{Fe}^{2+}(\text{aq})Fe3+(aq)+e−→Fe2+(aq) | +0.77+0.77+0.77 |
| Pb2+(aq)+2e−→Pb(s)\text{Pb}^{2+}(\text{aq}) + 2e^- \to \text{Pb}(\text{s})Pb2+(aq)+2e−→Pb(s) | −0.13-0.13−0.13 |
| Zn2+(aq)+2e−→Zn(s)\text{Zn}^{2+}(\text{aq}) + 2e^- \to \text{Zn}(\text{s})Zn2+(aq)+2e−→Zn(s) | −0.76-0.76−0.76 |
Give the oxidation state of vanadium in [VO2(H2O)4]+[\text{VO}_2(\text{H}_2\text{O})_4]^+[VO2(H2O)4]+.
