(Concentrated Hydrochloric Acid, Ph. Eur. monograph 0002)
HCl 36.46 7647-01-0
Preparation
Dilute Hydrochloric Acid
DEFINITION
Content
35.0 per cent m/m to 39.0 per cent m/m.
CHARACTERS
Appearance
Clear, colourless, fuming liquid.
Solubility
Miscible with water.
Relative density
About 1.18.
IDENTIFICATION
A. Dilute with water R. The solution is strongly acid (2.2.4).
B. It gives reaction (a) of chlorides (2.3.1).
C. It complies with the limits of the assay.
TESTS
Appearance of solution
To 2 mL add 8 mL of water R. The solution is clear (2.2.1) and colourless (2.2.2, Method II).
Free chlorine
Maximum 4 ppm.
To 15 mL add 100 mL of carbon dioxide-free water R, 1 mL of a 100 g/L solution of potassium iodide R and 0.5 mL of iodide-free starch solution R. Allow to stand in the dark for 2 min. Any blue colour disappears on the addition of 0.2 mL of 0.01 M sodium thiosulfate.
Sulfates (2.4.13)
Maximum 20 ppm.
To 6.4 mL add 10 mg of sodium hydrogen carbonate R and evaporate to dryness on a water-bath.
Dissolve the residue in 15 mL of distilled water R.
Residue on evaporation
Maximum 0.01 per cent.
Evaporate 100.0 g to dryness on a water-bath or using a rotary evaporator and dry the residue at 100-105 °C. The residue weighs a maximum of 10 mg.
ASSAY
Weigh accurately a ground-glass-stoppered flask containing 30 mL of water R. Introduce 1.5 mL of the acid to be examined and weigh again. Titrate with 1 M sodium hydroxide, determining the end-point potentiometrically (2.2.20).
1 mL of 1 M sodium hydroxide is equivalent to 36.46 mg of HCl.
STORAGE
In a stoppered container made of glass or another inert material, at a temperature not exceeding 30 °C.
