Titrations with transition metals

Question 1

What are titrations with transition metals known as?

Answer 1

Redox titrations

Question 2

What is the purpose of a redox titration?

Answer 2

To find out how much oxidising agent is needed to react with a quantity of reducing agent.

• easy to spot colour changes for redox titrations

Question 3

How to carry out a redox titration? (PRACTICAL)

Answer 3

1) Measure out a quantity of reducing agent using pipette and put it in a conical flask
2) Using a measuring cylinder, add 20cm3 of sulfuric acid to the flask.
3) Add oxidising agent to the reducing agent using a burette, swirling the conical flask.
4) oxidising agent reacts with the reducing agent, until all the reducing agent is used up, then the drop you add next to the flask will give the mixture the colour of an oxidising agent.
5) Stop when the mixture in the flask becomes tainted with the colour of the oxidising agent (end point) and record the volume of the oxidising agent added. THIS IS A ROUGH TITRATION
6) Then carry out some accurate titrations, do this until you get 2 or more readings that are concordant( within 0.1cm3 of each other)

Question 4

What is the main oxidising agent used for redox titrations?

Answer 4

Aqueous potassium manganate (VII), which contains PURPLE manganate (VII) ions.

Question 5

What conditions are needed for the manganate (VII) ions to be reduced?

Answer 5

Strong acidic conditions.