Preparation and standardisation of 0.1 N Perchloric acid IH volumetric solution
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 % 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, and determine the water content. 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, indicating freedom from Acetic anhydride.
OR Use readymade 0.1 M Perchloric acid.
Fill the titrant reservoir with 0.1N perchloric acid in glacial acetic acid. Accurately weight three times 55-60 mg THAM sample in to beakers, dissolve each in 50 ml of glacial acetic acid solution determining the end point potentiometrically.
Each 0.12114 g Tris (hydroxymethyl)-aminomethane (THAM) is equivalent to 1 mL of 0.1N perchloric acid
Normality (N) = [Weight of THAM (in g)]/[0.12114 x mL of perchloric acid solution (Titration reading – Blank reading)]
Limit: 0.1 N ± 5 % (0.0950 N – 0.1050 N)
3. PREPARATION OF INDICATORS / REAGENTS:
a. Glacial Acetic acid:
Glacial acetic acid to commerce for use in non-aqueous titrations.
It should comply with the following test:
Determine the water content of specimen of glacial acetic acid by titrimetric method. If the acid contains more than 0.4% of water, add a few mL of acetic anhdride, mix allow to stand overnight, and again determine the water.
4. STORAGE CONDITION:
Store in glass -stoppered bottles.