Preparation and Standardization of 0.1 M Perchloric acid : Pharmaceutical Guidelines

Preparation and Standardization of 0.1 M Perchloric acid

Preparation and standardisation of 0.1 M Perchloric acid using Potassium Biphthalate and Crystal Violet as indicator.

 Perchloric acid Solution Preparation:

•  Take about 500 ml of anhydrous glacial acetic acid  & about 25 ml Acetic anhydride in a cleaned and dried 1000 ml volumetric flask.
•  Add about 8.5 ml of Perchloric acid (About 70%) with continues stirring.
•  Cool the solution.
•  Make up the volume 1000-ml with anhydrous glacial acid. Mix solution thoroughly.
•  Keep the solution for at least (24 hours) for the excess acetic anhydride to be combined. Then carry out the determination of water. If the water content exceeds 0.05% add more acetic anhydride. If the solution contain water, add sufficient water to obtain a content of water between 0.02 % to 0.05%. Allow the solution to stand for 1 day and again titrate the water content. The solution so obtained should contain between 0.02% and 0.05% of water. Standardize the solution.

Related: Determination of Shelf Life of Solutions in Laboratory

Perchloric acid Solution Standardization:

•  Accurately weigh about 700 mg of Potassium phthalate, previously crushed lightly and dried at 120° for 2 hours, and dissolve it in 50 ml of glacial acetic acid in a 250-ml)conical flask.
•  Add 2 drops of Crystal Violet, and titrate with the perchloric acid solution until the violet color changes to blue-green.
•  Deduct the volume of the perchloric acid consumed by 50 ml of the glacial acetic acid.
•  Each 20.42 mg of Potassium phthalate is equivalent to 1 ml of 0.1N perchloric acid.
•  Calculate the molarity by following formula:

        KHC8H4Oin gm
N= ---------------------------
      0.20423 x HClOin ml





Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, 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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8 comments: Post Yours! Read Comment Policy ▼

  1. %RSD is not achieved in standardisation of 0.1 N perchloric acid by potiontometry

    What should I have to take precautions

    ReplyDelete
    Replies
    1. Calibrate potentiometer and check moisture content in perchloric acid.

      Delete
  2. Why acetic anhydride add in 0.1n hclo4.any mechanism is there

    ReplyDelete
    Replies
    1. It is added to keep it anhydrous.

      Delete
  3. Because of acetic acid also content some water so we add to acetic anhydried to manitant water content about below 0.5%

    ReplyDelete
  4. Please properly dried KHP than use for standardisation

    ReplyDelete
  5. Why do we take 8.5ml perchloric acid and 25ml glacial acetic acid?

    ReplyDelete
  6. Why acetic acid is added in preparation of perchloric acid.

    ReplyDelete

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