Oxidation-Reduction Titration

Topic Content:

Oxidation-reduction titration or Redox titration is a volumetric analysis involving an oxidizing agent and a reducing agent. In this titration, an oxidizing agent (also known as the oxidant) is titrated against a reducing agent (otherwise known as the reductant).

The unknown concentration of the analyte is then determined using calculations. At the end of it, the oxidizing agent becomes reduced and the reducing agent becomes oxidized. Examples of redox titration are potassium tetraoxomanganate(VII), iron(II) and thiosulphate-iodine titrations.

Redox Titrations of Acidified KMnO₄ Solution and a Fe²⁺ Salt:

Example 2.2.1:

When 0.011 mol dm^–3  potassium tetraoxomanganate(VII), KMnO_4(aq) solution acidified with teraoxosulphate(VI) acid was titrated against a solution containing 14.0 g of an iron(II) salt in 500 cm³  of solution, 21.30 cm³ of acidified KMnO_4(aq) oxidized 25.00 cm³ of the iron(II) salt solution.

The equation for the reaction is: 

MnO₄ ^– _(aq) + 5Fe²⁺ _(aq) + 8H⁺ _(aq) → Mn²⁺ _(aq) + 5Fe²⁺ _(aq) + 4H₂ O_(l)

(a) From the information provided, calculate the:

(i). moles of MnO₄ ^– used in