Preparation and standardization of 0.1 N Potassium Hydroxide, Methanolic USP Volumetric Solution
Dissolve about 6.8 g of Potassium hydroxide in 4 mL of water, and add Methanol to make 1000 mL. Allow the solution to stand in a tightly stoppered bottle for 24 hours. Then quickly decant the clear supernatant into a suitable, tight container.
Accurately measure about 25 mL of 0.1 N Hydrochloric acid VS. Dilute with 50 mL of water, add 2 drops of Phenolphthalein TS, and titrate with the methanolic Potassium hydroxide solution until a permanent, pale pink colour is produced.
Normality (N) = [Volume of HCl (in mL) x Normality of HCl]/[ Titration reading (in mL)]
Limit: 0.1 N ± 5 % (0.0950 N – 0.1050 N)
3. PREPARATION OF INDICATORS / REAGENTS :
a. 0.1 N Hydrochloric acid :
Preparation and standardization as per Doc. Ref. No.: D/VS/USP/022.
b. Phenolphthalein TS :
Dissolve 1 g of Phenolphthalein in 100 mL of alcohol.
4. STORAGE CONDITION :
Store in tightly stoppered bottles, protected from light.