Preparation and standardization of 0.05 M Potassium Hydroxide EP Volumetric Solution

1.  PREPARATION :

Dissolve 3 g of Potassium hydroxide in sufficient carbon dioxide free water to produce 1000 mL.

2. STANDARDISATION :

Titrate 20 mL of the Potassium hydroxide solution with 0.05 M Hydrochloric acid using 0.5 mL Phenolphthalein as indicator.

3. CALCULATION :

Molarity (M) = [Titration Reading (in mL) x Exact Molarity of 0.05 M HCL]/20

4. PREPARATION OF INDICATORS / REAGENTS :

a. 0.05 M Hydrochloric acid VS :

Preparation and standardisation as per respactive procedure.

b. Phenolphthalein solution :

Dissolve 0.1 g Phenolphthalein in 80 mL of Ethanol (96%) and dilute to 100 mL with water.

Test for sensitivity :  To 0.1 mL of the Phenolphthalein solution add 100 mL of carbon dioxide free water. The solution is colourless. Not more than 0.2 mL of 0.02 M Sodium hydroxide is required to change the colour to pink.

Colour change : pH 8.20 (colourless) to pH 10.00 (red).

5. STORAGE CONDITION :

Store in glass-stoppered bottles.