L5 - 7 - Redox Titrations

objectives

Applications

1. Solution of a range of redox titration problems.

Oxidising and Reducing Agents

Iodine Titrations

Used to estimate the concentration of a solution of an oxidising agent.

For example: to find the percentage of copper in an alloy (brass).

The combination of the reduction of Iodine with an oxidising agent can be observed below.

Videos explaining the iodometric titration method

How Copper is determined in Brass

1. Copper (II) ions in solution.
2. Iodide reacts with copper ions and liberates iodine. Producing a white ppte and brown solution.
3. Titrate with thiosulphate causes the brown colour to get lighter as Iodine is converted back to Iodide ions.
4. Near the end point, starch is added giving a blue black colour.
5. Finish titrating the thiosulphate until colourless.

Potassium manganate (VII) Titrations

Used to estimate the concentration of a solution of a reducing agent.

For example:

to find the dosage of iron in an iron sulfate tablet.

To find the concentration of ethanedioic acid in rhubarb leaves.

The combination of the Oxidation of Manganate with a reducing agent can be observed below.

Videos explaining the Manganate titration method