Preparation and standardization of 0.1 N Potassium Hydroxide USP Volumetric Solution

Preparation and standardization of 0.1 N Potassium Hydroxide USP Volumetric Solution

1.  PREPARATION:

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.

2. STANDARDISATION:

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.

Calculation:

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.

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