Preparation and Standardization of 0.1 M Sodium Hydroxide : Pharmaguideline

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Preparation and Standardization of 0.1 M Sodium Hydroxide

Preparation and standardisation of 0.1 M Sodium Hydroxide using Benzoic acid and Thymolphthalein solution as indicator.

Sodium Hydroxide Solution Preparation

  • Take about 100ml of distilled water in a cleaned and dried 1000 ml volumetric flask.
  • Add about 4.2 gm of Sodium hydroxide with continues stirring.
  • Add more about 700ml of distilled water, mix and allow to cool to room temperature.
  • Make up the volume 1000 ml with distilled water. Mix solution thoroughly.
  • Keep the solution for at least an hour and then carry out the standardization.

Sodium Hydroxide Solution Standardization

  • Accurately weigh about 0.5 g of potassium biphthalate, previously crushed lightly and dried at 120° for 2 hours.
  • Dissolve in 75 ml of carbon dioxide free water.
  • Add 2 drops of phenolphthalein, and titrate with the sodium hydroxide solution to the production of a permanent pink color.
  • Each 20.42 mg of potassium biphthalate is equivalent to 1 ml of 0.1N sodium hydroxide.

         Wt. in gm of potassium biphthalate
M= -----------------------------------------------------
             0.20423 x ml NaOH solution
Also see: Determination of Shelf Life of Solutions in Laboratory

Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
.moc.enilediugamrahp@ofni :liamENeed Help: Ask Question

3 comments: Post Yours! Read Comment Policy ▼

  1. Hi, As per USP 0.1N NaOH need to be standardised using Benzoic acid as primary standard. USP says to dissolve 200mg Benzoic acid in to 15 mL of water. But benzoic acid solubility iN water is very less and not completely dissolved. Can any one give light on this

  2. Hi we are also facing same issue at our R&D. Need to contact the USP for better clarity.


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