QUANTITATIVE ANALYSIS 449 When an amine, or a solution of its hydrochloride, is added to an aqueous solution of chloroplatinic acid, a salt of the base with the chloroplatinic acid, of general formula B^H 2 PtCU (where B is one molecule of the base) is formed and usually crystallises out, for these chloroplatinates have normally a rather low solubility in cold water. The chloroplatinate can be filtered off, dried, and then analysed by direct ignition, when only the metallic platinum ultimately remains. Knowing the percentage of platinum in the chloroplatinate, the molecular weight of the latter, and hence of the constituent base, can readily be calculated. Dissolve 0-2 ml. of pure aniline (or 0-2 g. of powdered p-toluidine) in 5 ml. of dilute hydrochloric acid (warming if necessary to obtain a clear solution). Pour this solution with stirring into a slight excess of chloroplatinic acid solution, e.g. , into about 10 ml. of a solution con-taining 5% of platinum as the chloroplatinic acid. The orange-yellow
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.