Preparation Of 0.1N Perchloric Acid (in Glacial Acetic Acid)

Preparation Of 0.1N Perchloric Acid (in Glacial Acetic Acid)
Molecular Formula:  HClO4			Molecular weight: 100.46
Preparation	:	Mix 8.5 mL of perchloric acid with 500 mL of glacial acetic acid and 21 mL of acetic anhydride, cool, and add glacial acetic acid to make 1000 mL. Alternatively, the solution may be prepared as follows. Mix 11 mL of 60 percent perchloric acid with 500 mL of glacial acetic acid and 30 mL of acetic anhydride, cool, and add glacial acetic acid to make 1000 mL. Allow the prepared solution to stand for 1 day for the excess acetic anhydride to be combined
Standardization	:	Accurately weigh about 700 mg of potassium biphthalate, previously crushed lightly and dried at  120ºC for 2 hours, and dissolve it in 50 mL of glacial acetic acid in a 250-mL flask. Add 2 drops of crystal violet TS, 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 biphthalate is equivalent to 1 mL of 0.1 N perchloric acid.     Preserve in glass-stoppered bottles, protected from light
Calculation	:	N = g KHC3H4O4 0.20423 X mL HClO4 Solution
Water Determination	:	Determine the water content by Method I (see Water Determination        921  ), except to use a test specimen of about 5 g of the 0.1 N perchloric acid that is expected to contain approximately 1 mg   of water and the Reagent (see Reagent under Method Ia in Water Determination   921  ) diluted such that 1 mL is equivalent to about 1 to 2 mg of water. If the water content exceeds 0.5%, add more acetic anhydride. If the solution contains no titratable water, add sufficient water to obtain a content of between 0.02% and 0.5% of water. Allow the solution to stand for 1 day, and again   titrate the water content. The solution so obtained contains between 0.02% and 0.5% of water, indicating freedom from acetic anhydride.
Reference	:	USP

 

0.1N Perchloric Acid