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
prepare-m50-solution-of-oxalic-acid-with-its-help-determine-50-the-molarity-and-strength-of-the-given-solution-of-potassium-permanganate-1
prepare-m50-solution-of-oxalic-acid-with-its-help-determine-50-the-molarity-and-strength-of-the-given-solution-of-potassium-permanganate-2

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
prepare-m50-solution-of-oxalic-acid-with-its-help-determine-50-the-molarity-and-strength-of-the-given-solution-of-potassium-permanganate-3

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.
prepare-m50-solution-of-oxalic-acid-with-its-help-determine-50-the-molarity-and-strength-of-the-given-solution-of-potassium-permanganate-4

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