Iron (III) catalyses the reaction between iodide and persulphate ions, in which

A. $\mathrm{Fe}^{3+}$ oxidises the iodide ion

B. $\mathrm{Fe}^{3+}$ oxidises the persulphate ion

C. $\mathrm{Fe}^{2+}$ reduces the iodide ion

D. $\mathrm{Fe}^{2+}$ reduces the persulphate ion

Choose the most appropriate answer from the options given below:

<p>To determine the correct answer to this question, let's analyze the catalysis mechanism involving Iron (III) in the reaction between iodide ($\mathrm{I^-}$) and persulfate ($\mathrm{S_2O_8^{2-}}$) ions.</p> <p>Iron (III), or $\mathrm{Fe}^{3+}$, can act as a catalyst by undergoing redox reactions, cycling between $\mathrm{Fe}^{2+}$ and $\mathrm{Fe}^{3+}$. Here’s how it typically works:</p> <p>1. $\mathrm{Fe}^{3+}$ can oxidize iodide ions to iodine. The reaction will proceed as follows:</p> <p>$\mathrm{2Fe^{3+} + 2I^- \rightarrow 2Fe^{2+} + I_2}$</p> <p>2. $\mathrm{Fe}^{2+}$, now formed, can be oxidized back to $\mathrm{Fe}^{3+}$ by reducing persulfate ions. The reaction will be:</p> <p>$\mathrm{2Fe^{2+} + S_2O_8^{2-} \rightarrow 2Fe^{3+} + 2SO_4^{2-}}$</p> <p>Based on this mechanism, $\mathrm{Fe}^{3+}$ is responsible for oxidizing the iodide ions, and $\mathrm{Fe}^{2+}$ is responsible for reducing the persulfate ions. Thus, we can conclude:</p> <p>A. $\mathrm{Fe}^{3+}$ oxidises the iodide ion: This statement is correct.</p> <p>B. $\mathrm{Fe}^{3+}$ oxidises the persulphate ion: This statement is incorrect because $\mathrm{Fe}^{3+}$ does not oxidize persulfate ions.</p> <p>C. $\mathrm{Fe}^{2+}$ reduces the iodide ion: This statement is incorrect because $\mathrm{Fe}^{2+}$ does not reduce iodide ions.</p> <p>D. $\mathrm{Fe}^{2+}$ reduces the persulphate ion: This statement is correct.</p> <p>Therefore, the most appropriate answer is:</p> <p><strong>Option C: A and D only</strong></p>