Preparation and standardization of 0.5 M Hydrochloric acid EP Volumetric Solution
1. PREPARATION :
Dilute 51.5 g of Hydrochloric acid to 1000.0 mL with water.
2. STANDARDISATION :
Dissolve 475 mg of Trometamol in 50 mL of water. Titrate with the hydrochloric acid solution, determining the end point potentiometrically or using 0.1 mL of Methyl orange solution as indicator until a yellowish-red colour is obtained.
1 mL of 0.5 M Hydrochloric acid is equivalent to 60.55 mg of C4H11NO3.
Molarity (M) = [0.5 x Weight of Trometamol (in mg)]/[Titration reading (in mL) x 60.55]
Limit: 0.5 M ± 5 % (0.4750 M – 0.5250 M)
3. PREPARATION OF INDICATORS / REAGENTS :
a. Methyl orange solution :
Dissolve 0.1 g of Methyl orange in 80 mL of water and dilute to 100 mL with Ethanol (96 %).
Test for sensitivity : A mixture of 0.1 mL of the Methyl orange solution and 100 mL of carbon dioxide free water is yellow. Not more than 0.1 mL of 1 M Hydrochloric acid is required to change the colour to red.
Colour change : pH 3.0 (red) to pH 4.4 (yellow).
4. STORAGE CONDITION :
Store in glass stoppered bottle.