Question

How to make N/20 KMnO4 solution

Answer 1

Chemical equation

refer fig 1

Indicator

KMnO4 is a self-indicator.

Endpoint

Colourless to permanent pink colour (KMnO4 in burette).

Procedure

Rinse and fill the burette with the given KMnO4 solution.

Weigh exactly 1.58 g of oxalic acid crystals and dissolve in water to prepare 500 ml of

its solution using a 500 ml measuring flask. Rinse the pipette with the N/20 oxalic acid

solution and pipette out 20 ml of it in a washed titration flask.

Add one test tube (~ 20 ml) full of dilute sulphuric acid (~ 4 N) to the solution in , titration flask.

Note the initial reading of the burette.

Heat the flask to 60-70°C and add KMnO4 solution from the burette till a permanent light pink colour is just imparted to the solution in the titration flask.

Note the final reading of the burette.

Repeat the above steps 4-5 times to get three cdncordant readings.

Observations

Refer fig2

Calculations

Refer fig3