Problem 1: A saturated aqueous solution of magnesium methanoate, Mg(HCOO)₂, has a solubility of approximately 150 g dm^-3 at room temperature. Its exact solubility can be determined by titrating magnesium methanote against aqueous potassium manganate (VII).

During the titration, the methanoate ion, HCOO^-, is oxidizes to carbon dioxide while the manganate (VII) ion, MnO₄^-, is reduced to Mn²⁺.

You are supplied with

A saturated aqueous solution of Mg(HCOO)₂

Aqueous potassium manganate (VII), KMnO₄, of concentration 0.0200 mol dm^-3

(a) (i). write the half equations for the oxidation of HCOO-(aq) to CO₂(g) and the reduction of MnO₄-(aq) to Mn²⁺ (aq) in acid solution.

(ii) Using the approximately solubility above, calculate the concentration, in mol dm^-3, of the saturated aqueous magnesium methanoate and the concentration of the methanoate ions present in this solution

(Ai: H, 1.0, C, 12.0, O, 16.0, Mg, 24.3)

(iii) In order to obtain a reliable titre value, the saturated solution of magnesium methanoate needs to be diluted.

Describe how you would accurately measure a 5.0cm³ sample of saturated magnesium methanate solution and use it to prepare a solution fifty times more dilute than the saturated solution.

(vi) 1 mol of acidified MnO₄^- ions reacts with 2.5 mol of HCOO^- ions.

25.0 cm³ of the diluted solution prepared in (iii) required 25.5 cm³ of 0.0200 mol dm^-3 potassium manganate (VII) solution to reach the end point.

Use this information to calculate the concentration, in mol dm^-3, of HCOO- ions in the diluted solution.