0.1M Perchloric Acid Preparation and Standardization Procedure (IP Method)

Know the step-by-step procedure used to prepare and standardize 0.1M perchloric acid solution as per IP guidelines. Incorporates reagents, equipment, calculation, detection of endpoint, storage of reagents, and standardization with potassium hydrogen phthalate (KHP).

1.0 Scope:

This procedure is applicable for preparation and standardization of 0.1M perchloric acid.

2.0 Apparatus:

• Auto titrator
• 1000 ml volumetric flask
• 250 ml glass-stoppered conical flask
• 25 ml and 50 ml volumetric pipette
• 100 ml volumetric flask

3.0 Reagents:

• Perchloric acid AR grade
• Potassium hydrogen phthalate AR grade
• Crystal violet solution
• Anhydrous glacial acetic acid AR grade
• Acetic anhydride AR grade

Related: 0.1 N Perchloric Acid Preparation and Standardization

Preparation of Reagents for 0.1M Perchloric Acid:

Crystal violet solution:

• Dissolve 0.5 g of crystal violet in a 50 ml of anhydrous glacial acetic acid to produce 100 ml with anhydrous glacial acetic acid and store in a well fitted transparent glass bottle.
• Add 8.5 ml of perchloric acid, 500 ml of anhydrous glacial acetic acid and 25 ml of acetic anhydride. Let it cool. Next, add the anhydrous glacial acetic acid to make up to 1000 ml.
• Allow to stand for a full day. This allows extra acetic anhydride to react. Next, test the water level.
• Add a little more acetic anhydride if the water content is greater than 0.05%. If there is no titrable water in it, pour a little of it in. The target is to have a water content of 0.02% to 0.05%.
• Wait for one more day and test the water once again. Continue adjusting to maintain this 0.02% – 0.05% window.

5.0 Standardization of 0.1M Perchloric Acid

• Dry some KHP in small quantities, sprinkling with powder and then drying at 120 °C for 2 hrs. Measure out 0.35 g of it. Dissolve in 50 ml of anhydrous glacial acetic acid.
• Drop in 0.1 ml of the crystal violet solution. Now, titrate with your 0.1M perchloric acid. When the color turns from violet to emerald-green, stop.
• Do a blank test also and make adjustments in the numbers as necessary. Keep in mind that 1 mL of a 0.1M perchloric acid is the equivalent of 0.02042 g of C₈H₅KO₄.

6.0 Calculation:

Where:
N = molarity of perchloric acid solution
W = weight of potassium hydrogen phthalate in g
V = volume of 0.1M perchloric acid solution in ml

7.0 Storage:

Store in a well fitted amber colour glass bottle.

8.0 Reference:

As per IP –96 Page No. A-211