Preparation and Standardisation of 0.01 M Hydrochloric acid EP Volumetric Solution
Dilute 10.3 g of Hydrochloric acid to 1000 ml with water. Further dilute 100 ml of this solution to 1000 ml with water.
Dissolve 0.100 g of Sodium carbonate in 20 ml of water, add 0.1 ml of Methyl orange solution, and Titrate with the Hydrochloric acid until the solution just becomes yellowish red. Boil for about 2 minutes. The solution reverts to yellow. Cool and continue the titration until a yellowish red colour is obtained.
1 ml of 0.01 M Hydrochloric acid is equivalent to 0.00053 g of Na2CO3.
Molarity (M) = (0.01 x Weight of Sodium carbonate (in g))/ (Titration reading (in ml) x 0.00053)
Limit: 0.01 M ± 5 % (0.0095 M – 0.0105 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 bottles.