Preparation and standardization of 0.1 N Potassium Hydroxide, Methanolic USP Volumetric Solution

1.  PREPARATION:

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.

2. STANDARDISATION:

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.

Calculation :

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.