6.2.6 Redox Titrations

Question 1

What is a redox titration?

Answer 1

• Oxidising agent being titrated against a reducing agent
• Self indicating
• 2 common ones are manganate (VII) and dichromate (VI) titrations

Question 2

How is potassium manganate used in redox titrations?

Answer 2

• KMNO4
• An oxidising agent
• Deep purple colour
• In acidic solutions, reduced from Mn 7+ to nearly colourless Mn (II)
  ions (ion is actually pink)
  .
• KMNO3 solution in burette
• Titrated with reducing agent to make solution colourless
• at endpoint, MNO3- ion in excess so first appearance of a permanent colour change marks endpoint
• Colour seen is pink, if purple the endpoint has been overshot, too much MNO3- in excess
• Typical reducing agent is Iron(II) sulphate tablets

Question 3

Answer 3

Question 4

How is Potassium Dichromate used in redox titrations?

Answer 4

• Oxidising agent
• Cr goes from 6+ to 3+
• Orange to Green
• Acidified with excess dilute sulphuric acid (H+ required)

Question 5

How to obtain balanced redox equation

Answer 5