Preparation and standardization of 0.1 N Potassium Permanganate USP Volumetric Solution
1. PREPARATION:
Dissolve about 3.3 g of Potassium permanganate in 1000 ml of water in a flask, and boil the solution for about 15 minutes. Insert the stopper in the flask, allow it to stand for at least 2 days, and filter through a fine porosity, sintered glass crucible. If necessary, the bottom of the sintered glass crucible may be lined with a pledget of glass wool.
2. STANDARDISATION:
Accurately weigh about 200 mg of Sodium oxalate, dried according to the instruction on its label, and dissolve it in 250 ml of water. Add 7 ml of Sulfuric acid, heat to about 70°C, and then slowly add the Permanganate solution from burette, with constant stirring, until a pale pink colour, which persists for 15 seconds, is produced. The temperature at the conclusion of the titration should be not less then 60°C.
Each 6.700 mg of Sodium oxalate is equivalent to 1 ml of 0.1 N Potassium permanganate.
Note: Since Potassium permanganate is reduced on contact with organoc substances such as rubber, the solution must be handled in apparatus entirely of glass or other suitability inert material.
Calculation:
Normality (N) = [Weight of Na2C2O4 (in g)]/[0.06700 x Titration reading (in ml)]
Limit: 0.1 N ± 5 % (0.0950 N – 0.1050 N)
3. STORAGE CONDITION:
Store in glass stoppered, amber coloured bottles.