When a monograph specifies that an article responds to the test for dry chlorides, mix the solid to be tested with an equal weight of manganese dioxide, moisten with sulfuric acid, and gently heat the mixture: chlorine, which is recognizable by the production of a blue color with moistened starch iodide paper, is evolved. As was the case with the chlorides, the bromides and iodides also form precipitates when they are reacted with silver nitrate. ![]() Add ammonia TS dropwise to this precipitate. Wash the precipitate with three 1-mL portions of nitric acid solution (1 in 100), and discard the washings. ![]() When the soluble silver(I) nitrate salt solution is combined with the soluble sodium chloride salt solution, a white precipitate of silver(I) chloride is produced. Centrifuge the mixture without delay, and decant the supernatant layer. Understanding: Solubility rules state that nitrate salts are soluble in water, and silver nitrate is no exception. When testing amine (including alkaloidal) hydrochlorides that do not respond to the above test, add one drop of diluted nitric acid and 0.5 mL of silver nitrate TS to a solution of the substance being examined containing, unless otherwise directed in the monograph, about 2 mg of chloride ion in 2 mL: a white, curdy precipitate is formed. AgNO3 (aq) + KCl (aq) KNO3 (aq) + AgCl (s). ![]() With silver nitrate TS, solutions of chlorides yield a white, curdy precipitate that is insoluble in nitric acid but is soluble in a slight excess of 6 N ammonium hydroxide. Silver nitrate appears as a colorless or white crystalline solid becoming black on exposure to light or organic material. This demonstration makes a white precipitate by mixing equal amounts of silver nitrate and potassium chloride.
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