Which ion cannot catalyse the reaction between iodide (I−\text{I}^-I−) and peroxodisulfate (S2O82−\text{S}_2\text{O}_8^{2-}S2O82−)?
Use the data below to help you answer this question.
Half-equationEθ/VS2O82−+2e−→2SO42−+2.01Ce4++e−→Ce3++1.70Fe3++e−→Fe2++0.77I2+2e−→2I−+0.54V3++e−→V2+−0.26 \begin{array}{|c|c|} \hline \textbf{Half-equation} & E^\theta / \text{V} \\ \hline \text{S}_2\text{O}_8^{2-} + 2e^- \rightarrow 2\text{SO}_4^{2-} & +2.01 \\ \hline \text{Ce}^{4+} + e^- \rightarrow \text{Ce}^{3+} & +1.70 \\ \hline \text{Fe}^{3+} + e^- \rightarrow \text{Fe}^{2+} & +0.77 \\ \hline \text{I}_2 + 2e^- \rightarrow 2\text{I}^- & +0.54 \\ \hline \text{V}^{3+} + e^- \rightarrow \text{V}^{2+} & -0.26 \\ \hline \end{array} Half-equationS2O82−+2e−→2SO42−Ce4++e−→Ce3+Fe3++e−→Fe2+I2+2e−→2I−V3++e−→V2+Eθ/V+2.01+1.70+0.77+0.54−0.26Ce3+\text{Ce}^{3+}Ce3+
V2+\text{V}^{2+}V2+
Fe2+\text{Fe}^{2+}Fe2+
Fe3+\text{Fe}^{3+}Fe3+
63 exam-style questions on AQA A Level Chemistry Transition metals (A-level only), covering General properties of transition metals (A-level only), Substitution reactions (A-level only), Shapes of complex ions (A-level only), Formation of coloured ions (A-level only), Variable oxidation states (A-level only), and Catalysts (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.