Question

Complete and balance the following chemical equations: (a) \[ 2MnO_4^-(aq) + 10I^-(aq) + 16H^+(aq) \rightarrow \] (b) \[ Cr_2O_7^{2-}(aq) + 6Fe^{2+}(aq) + 14H^+(aq) \rightarrow \] 

Hint:

In redox reactions, the oxidizing agent is reduced, and the reducing agent is oxidized. Pay attention to the stoichiometric coefficients when balancing the equation.

Answer 1

(a) Reaction of permanganate with iodide ions: In an acidic solution, permanganate ions (\(MnO_4^-\)) act as an oxidizing agent and oxidize iodide ions (\(I^-\)) to iodine (\(I_2\)). The balanced equation shows the reduction of permanganate to \(Mn^{2+}\) and the oxidation of iodide to iodine. \[ 2MnO_4^-(aq) + 10I^-(aq) + 16H^+(aq) \rightarrow 2Mn^{2+}(aq) + 5I_2(aq) + 8H_2O(l) \] (b) Reaction of dichromate with iron(II) ions: In an acidic solution, dichromate ions (\(Cr_2O_7^{2-}\)) are reduced to chromium(III) ions (\(Cr^{3+}\)), while iron(II) ions (\(Fe^{2+}\)) are oxidized to iron(III) ions (\(Fe^{3+}\)). \[ Cr_2O_7^{2-}(aq) + 6Fe^{2+}(aq) + 14H^+(aq) \rightarrow 2Cr^{3+}(aq) + 6Fe^{3+}(aq) + 7H_2O(l) \]