Which ion cannot catalyse the reaction between bromide (Br−\text{Br}^-Br−) 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−+2.01Co3++e−→Co2++1.82Ce4++e−→Ce3++1.70Mn3++e−→Mn2++1.51Br2+2e−→2Br−+1.09Fe3++e−→Fe2++0.77 \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{Co}^{3+} + e^- \rightarrow \text{Co}^{2+} & +1.82 \\ \hline \text{Ce}^{4+} + e^- \rightarrow \text{Ce}^{3+} & +1.70 \\ \hline \text{Mn}^{3+} + e^- \rightarrow \text{Mn}^{2+} & +1.51 \\ \hline \text{Br}_2 + 2e^- \rightarrow 2\text{Br}^- & +1.09 \\ \hline \text{Fe}^{3+} + e^- \rightarrow \text{Fe}^{2+} & +0.77 \\ \hline \end{array} Half-equationS2O82−+2e−→2SO42−Co3++e−→Co2+Ce4++e−→Ce3+Mn3++e−→Mn2+Br2+2e−→2Br−Fe3++e−→Fe2+Eθ/V+2.01+1.82+1.70+1.51+1.09+0.77Mn2+\text{Mn}^{2+}Mn2+
Ce3+\text{Ce}^{3+}Ce3+
Fe2+\text{Fe}^{2+}Fe2+
Co2+\text{Co}^{2+}Co2+
