Preparation of 1 N Sodium hydroxide volumetric solution.
➤ Glass ware and instruments required.
Beaker, Glass stirrer, Graduated Pipettes, Graduated cylinder, Analytical balance, Sucker, Volumetric flask, Fume hood.
➤ Reagents required.
Sodium hydroxide.
Molecular wt NaOH , 40.0
Potassium hydrogen phthalate primary standard. (Previously dried for 2 hour at 120°C)
Phenolphthalein indicator.
➤ Preparation.
Weigh 42 g Sodium hydroxide pallets reagent grade in beaker add 250 mL of water and dissolve it. Solution become warm, cool to room temperature, filter through filter paper and transfer to 1000 mL volumetric flask. Dilute up to the mark with water and transfer to tight polypropylene container.
➤ Standardisation.
Weigh about 5 g Potassium hydrogen phthalate in 250 mL conical flask. Disolve in 100 mL water. Add 2 drops of Phenolphthalein indicator solution and titrate with prepared 1 N NaOH volumetric solution tilll the solution becomes permanent pink.
➤ Calculations.
Wt. of KHC8H4O4× 1
Normality = --------------------------------------------
0.2042 × Burette reading in mL
➤ Note. (Sodium hydroxide solution is not kept in glass bottles because it reacts with glass to form silicon hydroxide.)
(Polypropylene are mainly made of carbon-carbon single bond which is chemically stable to many external stimuli. NaOH, as a base, tend to break down ester bond (O=C-O) easily (via hydrolysis route). But for single bond, there is typically no reaction to break it.)
➤ Note. (Sodium hydroxide solution is not kept in glass bottles because it reacts with glass to form silicon hydroxide.)
(Polypropylene are mainly made of carbon-carbon single bond which is chemically stable to many external stimuli. NaOH, as a base, tend to break down ester bond (O=C-O) easily (via hydrolysis route). But for single bond, there is typically no reaction to break it.)
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