Manganate (VII) Redox Titrations

Question 1

Describe the basic procedure for carrying out Manganate (VII) titrations.

Answer 1

1. A standard solution of potassium manganate is added to the burette
2. Using a pipette, add a measured volume of the solution being analysed to the conical flask and add an excess of sulphuric acid to provide H+ ions which are required for the reduction of MnO4- ions.
3. During the titration, the manganate (VII) solution reacts and is decolourised and the end point is dictated by the first permanent pink colour
4. Repeat titration until you have at least two concordant results

Question 2

Why is the meniscus read from the top during this titration?

Answer 2

KMnO4- is a deep purple colour so it is difficult to see the bottom of the meniscus

Question 3

How is percentage purity calculated?

Answer 3

(Mass of pure hydrated salt / mass of impure) x100

Question 4

What is the ratio of moles of Fe2+ to moles of FeSO4*7H2O?

Answer 4

1:1