Preparation and standardization of 0.1 N Potassium Hydroxide USP Volumetric Solution
Dissolve 6.8 g of Potassium hydroxide in about 950 ml of water. Add a freshly prepared saturated solution of Barium hydroxide until no more precipitate forms. Shake the mixture thoroughly and allow it to stand overnight in a stopper bottle. Decant the clear liquid, or filter the solution in a tight, Polyolefin bottle.
Accurately weigh about 0.5 g of Potassium biphthalate, previously crushed lightly and dried at 120°C for 2 hours, and dissolve in 75 ml of carbon dioxide free water. Add 2 drops Phenolphthalein TS, and titrate with the 0.1 N Potassium hydroxide solution to the production of a permanent pink color.
Each 204.23 mg of Potassium biphthalate is equivalent to 1 ml of 1 N Potassium hydroxide.
Normality (N) = [Weight of KHC8H4O4 (in g)]/ [0.20423 x Titration reading (in ml)]
Limit: 0.1 N ± 5 % (0.0950 N – 0.1050 N)
3. PREPARATION OF INDICATORS / REAGENTS:
a. Phenolphthalein TS:
Dissolve 1 g of Phenolphthalein in 100 ml of alcohol.
4. STORAGE CONDITION:
Store in tightly closed polyolefin bottle.