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Preparation and Standardization of 0.1 M Ethanolic Sodium Hydroxide

Prepararation and standardisation of 0.1 M Ethanolic Sodium Hydroxide using Benzoic acid and Thymolphthalein solution as indicator used for pharmaceutical analysis.

Ethanolic Sodium Hydroxide Solution Preparation

  • Dissolve 4.2 g of sodium hydroxide in 5 ml of water.
  • Add sufficient aldehyde-free ethanol to produce 1000 ml.
  • Allow the solution to stand in a tightly-stoppered bottle for 24 hours.
  • Then quickly decant the clear supernatant liquid into a suitable, tightly-closed container.
  • Standardize the solution in the following manner.

Ethanolic Sodium Hydroxide Solution Standardization

  • Weigh accurately about 0.6 g of Benzoic acid.
  • Dissolve in a mixture of one ml of ethanol (95 percent) and 6 ml of water and titrate with the ethanolic sodium hydroxide solution, using 0.2 ml of Thymolphthalein solution as indicator. 
  • 1 ml of 0.1 M ethanolic sodium hydroxide is equivalent to 0.01221g of C7H6O2.
  • Store protected from light and moisture.
  • Calculate the molarity of solution by the following formula:
                      C7H6O2 in mg
M = ------------------------------------------------------
        Ethanolic Sodium Hydroxide in ml x 12.21
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.
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