Strong Ammonia Solution
» Strong Ammonia Solution is a solution of NH3, containing not less than 27.0 percent and not more than 31.0 percent (w/w) of NH3. On exposure to air it loses ammonia rapidly.
CautionUse care in handling Strong Ammonia Solution because of the caustic nature of the Solution and the irritating properties of its vapor. Cool the container well before opening, and cover the closure with a cloth or similar material while opening. Do not taste Strong Ammonia Solution, and avoid inhalation of its vapor.
Packaging and storage Preserve in tight containers, at a temperature not above 25.
Identification Hold a glass rod moistened with hydrochloric acid near the surface of the Solution: dense, white fumes are produced.
Heavy metals, Method I 231 Evaporate 1.7 mL on a steam bath to dryness, add to the residue 1 mL of 3 N hydrochloric acid, and evaporate to dryness. Dissolve the residue in 2 mL of 1 N acetic acid, and dilute with water to 25 mL: the limit is 0.0013%.
Limit of nonvolatile residue Evaporate a 10-mL portion in a tared platinum or porcelain dish to dryness, and dry at 105 for 1 hour: not more than 5 mg of residue remains (0.05%).
Readily oxidizable substances To a mixture of 4.0 mL of Solution and 6 mL of water add a slight excess of 2 N sulfuric acid and 0.10 mL of 0.1 N potassium permanganate: the pink color does not completely disappear within 10 minutes.
Assay Transfer quickly a portion of Solution to a stoppered, thick-walled container (a pressure bottle is suitable) to obtain a column height of about 20 cm, insert the stopper, and cool the container and contents to 10 or lower. Weigh accurately a glass-stoppered, 125-mL conical flask containing 35.0 mL of 1 N sulfuric acid VS. Insert a graduated 10-mL measuring pipet into the cooled Solution, allow the liquid to rise in the pipet without vacuum, remove the pipet, wipe off adhering liquid, and discard the first mL of the Solution permitted to run from the pipet. Hold the pipet just above the surface of the 1 N sulfuric acid VS in the conical flask, and transfer about 2 mL of the Solution into the flask. Insert the stopper, mix, and again weigh to obtain the weight of the specimen. Titrate the excess acid with 1 N sodium hydroxide VS, using methyl red TS as the indicator. Perform a blank determination (see Residual Titrations under Titrimetry 541). Each mL of 1 N sulfuric acid is equivalent to 17.03 mg of NH3.