Preparation and standardization of 0.1 N Sodium Hydroxide USP Volumetric Solution
Dissolve 16.2 g of Sodium hydroxide in 150 mL of carbon dioxide free water, cool the solution to room temperature, and filter through hardened filter paper. Transfer 54.5 mL of the clear filtrate to a tight, polyolefin container, and dilute with carbon dioxide free water to 1000 mL.
Accurately weigh about 0.5 g of Potassium biphathalate, previously crushed lightly and dried at 120°C for 2 hours, and dissolve in 75 mL of carbon dioxide free water. Add 2 drops of Phenolphthalein TS, and titrate with the Sodium hydroxide solution to the production of a permanent pink colour or by potentiometrically.
Each 204.22 mg of Potassium biphthalate is equivalent to 1 mL of 0.1 N Sodium hydroxide.
Normality (N) = [Weight of KHC8H4O4 (in g)]/[ 0.20422 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 glass stoppered bottles.