![]() ![]() Includes kit list and safety instructions. 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. The above reaction equation involves steps of magnesia dissolution followed by magnesium hydroxide precipitation (Birchal et al., 2001 and Rocha et al., 2004). Students react magnesium sulfate and sodium carbonate to form magnesium carbonate, which is insoluble in water. Add ammonia TS dropwise to this precipitate. Hematite occurs in a variety of forms, colors and lusters, from shiny metallic silver to. Wash the precipitate with three 1-mL portions of nitric acid solution (1 in 100), and discard the washings. An example of this property is seen in the iron-oxide mineral hematite. Centrifuge the mixture without delay, and decant the supernatant layer. 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. 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. Temporary hardness (Carbonate hardness) is caused by the presence of dissolved bicarbonates of Calcium, Magnesium, Iron and other heavy. ![]()
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