a. In the presence of acid, the manganate(VII) ion is a powerful oxidising agent. The half-equation for its reduction in acid solution is:

MnO₄^–(aq) + 8H⁺(aq) + 5e^– ⇌ Mn²⁺(aq) + 4H₂O(l)  E^θ= +1.51 V

i. Explain why the presence of an acid is necessary for the Mn₄^–(aq) to function as an oxidising agent.

ii. Give two reasons for the MnO₄ ^–(aq) acting as an oxidising agent in acidic solution.

b. Iodide ions are oxidised to iodine according to the half-cell equation: 

1/2 I₂(aq) + e^– ⇌ I^–(aq) E^θ = +0.54 V

i. Explain why an acidified solution of manganate(VII) ions can be used to oxidise iodide ions to iodine.

ii. Write the balanced equation for this reaction.