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Experiments on Redox Reactions

Let us become familiar with method of performing the experiments on redox titrations between following pairs:

MnO 4 versus Fe2+ and C2 O42-

I2/ KI versus S2 O3 2-ions


1. Titrations of MnO4 versus Fe2+ and C2O42-

chemical reaction involved in these titrations are

Some important points are:

• KMnO 4 solution is taken in burette.

• Solution of Fe2+ salt or C2O42- salts are taken in titration flask.

• Sufficient-dilute H2SO4 is added to titration flask to provide acidic medium.

• End point is from colourless solution to light pink colour.

• In case of C2O42- salt the solution in titration flask should be heated to about 60°C before the addition of KMnO4 solution to provide sufficient activation energy. (Follow Activity 32.1.)


2. Titration of I2 / KI versus S2O32- salt

The chermical reaction involved in this titration is

In this titration,

  • I2 / KI solution is taken in burette.
  • Aqueous solution of S2O32- salts is taken in the titration flask.
  • Indicator used is freshly prepared starch solution.
  • Indicator should be added towards the end of the
  • titration when the solution acquires lime yellow colour.
  • The end point is appearance of blue colour.