Preparation and Standardization of 0.1 N Perchloric acid : Pharmaguideline

Online GMP Courses with Certificate


Preparation and Standardization of 0.1 N 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 contains 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 the following formula:
        KHC8H4Oin gm
N= ---------------------------
      0.20423 x HClOin ml

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

15 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

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

    2. What is procedure for water content determination

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

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

  4. Please properly dried KHP than use for standardisation

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

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

  7. please anybody can give me the reaction mechanism??

  8. hello mr ankur , i just wanna ask about the end point of hclo4 standardization, is it blue-green or yellowish green (emerald green) because in other references said that, and i always trying to make it in blue-green but i never got the value exactly, because the range of blue-green to yellowish green is far enough. would you please thanks :D

    1. That is very slight change from violet to blue green, look it carefully.

  9. To make it simple and to understand the exact color change, please add the indicator (crystal violet) while doing potentiometric standardization of 0.1 M Perchloric acid VS. You will find the exact color change at exact endpoint.

  10. How to make 0.1N per chlororic acid

  11. Hi would you like to guide me either 0.1 m and 0.1 N of perchloric are same plz tell how to prepare


Please don't spam. Comments having links would not be published.

Popular Categories

QA SOPs QC SOPs Micro SOPs HVAC Production SOPs Stores SOPs Checklists Maintenance SOPs HPLC Sterile GLP Validation Protocols Water System GDP Regulatory Maintenance Calibration Warning Letters Education B.Pharmacy
Online Courses

Follow Pharmaguideline



Editable Pharmaceutical Documents in MS-Word Format. Ready to use SOPs, Protocols, Master Plans, Manuals and more...



Recent Posts