Which of the following specific redox half-reactions properly represent the potent, classic oxidisin — d and f Block Elements Chemistry Question

💡 Solution & Explanation

In acidic solution, $Cr_2O_7^{2-}$ is a powerful oxidising agent, gaining $6$ electrons to form $2Cr^{3+}$. This highly positive reduction potential enables it to seamlessly strip electrons from multiple reducing agents: $Sn^{2+} \rightarrow Sn^{4+} + 2e^-$; $2I^- \rightarrow I_2 + 2e^-$; $Fe^{2+} \rightarrow Fe^{3+} + e^-$; and crucially, when reacting with $HCl$, it oxidizes the chloride ions: $14HCl + K_2Cr_2O_7 \rightarrow 2KCl + 2CrCl_3 + 7H_2O + 3Cl_2$.