Preparation and standardization of 1 M Sodium Hydroxide BP Volumetric Solution
Dissolve 42 g of Sodium hydroxide in carbon dioxide free water and dilute to 1000 mL with same solvent.
Dissolve 1.50 g of Potassium hydrogen phthalate in 50 mL of water. Titrate with the Sodium hydroxide solution, determining the end point potentiometrically or using 0.1 mL of Phenolphthalein solution as indicator.
1 mL of 1 M Sodium hydroxide is equivalent to 204.2 mg of C8H5KO4.
Molarity (M) = [1 x Weight of Potassium hydrogen phthalate (in g)]/ [0.2042 x Titration reading (in mL)]
Limit: 1 M ± 5 % (0.9500 M –1.0500 M)
3. PREPARATION OF INDICATORS / REAGENTS:
a. Phenolphthalein solution :
Dissolve 0.1 g of Phenolphthalein in 80 mL of Ethanol (96 %) and dilute to 100 mL with water.
4. STORAGE CONDITION:
Store in glass-stoppered bottles.