Prepare M/50 Solution of Oxalic Acid. With its help, Determine 50 the Molarity and Strength of the Given Solution of Potassium Permanganate

Prepare M/50 Solution of Oxalic Acid. With its help, Determine 50 the Molarity and Strength of the Given Solution of Potassium Permanganate (KMnO₄)

Chemical Equations

Indicator
KMnO₄ is a self-indicator.

End Point
Colourless to permanent pink colour (KMnO₄ in burette).

Procedure

1. Weigh 1.260 g of oxalic acid crystals and dissove them in water to prepare 500 ml of M/50 oxalic acid solution using a 500 ml measuring flask. Rinse the pipette with the M/50 oxalic acid solution and pipette out 20 ml of it in a washed titration flask.
2. Rinse and fill the burette with M/100 KMnO₄ solution.
3. Add one test-tube (~ 20 ml) full of dilute sulphuric acid (~ 2 M) to the solution in titration flask.
4. Note the initial reading of the burette.
5. Now add KMnO₄ solution from the burette till a permanent light pink colour is imparted to the solution in the titration flask on addition of last single drop of KMnO₄ solution.
6. Note the final reading of the burette.
7. Repeat the above steps 4-5 times to get a set of three concordant readings.

Observations
Weight of watch glass =……. g
Weight of watch glass + Mohr’s salt =…………..g
Weight of Mohr’s salt = 1.260 g
Volume of Mohr’s salt solution prepared = 500 ml
Volume of Mohr’s salt solution taken for each titration = 20.0 ml
Molarity of KMnO₄ solution =M/50

Calculations
(a) Molarity of the KMnO₄ solution
From the overall balanced chemical equation it is clear that 2 moles of KMnO₄ react with 5 moles of oxalic acid.