An Introduction to Chemical Science by Rufus Phillips Williams
page 82 of 262 (31%)
page 82 of 262 (31%)
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of water falls; this absorbs it. The yellow color in most
commercial HCl indicates impurities, some of which are Fe, S, As, and organic matter. As, S, etc., come from the pyrites used in making H2SO4. Chemically pure (C.P.) acid is freed from these, and is without color. The gas may be dried by passing it through a glass tube holding CaCl2 (Fig. 16) and collecting it over mercury. The muriatic acid of commerce consists of about two- thirds water by weight. HCl can also be made by direct union of its constituents.81. Uses.--HCl is used to make Cl, and also bleaching- powder. Its use as a reagent in the laboratory is illustrated by the following experiment:-- Experiment 49.--Put into a t.t. 2 cc. AgNO3 solution, add 5 cc. H2O, then add slowly HCl so long as a ppt. (precipitate) is formed. This ppt. is AgCl. Now in another t.t. put 2 cc. Cu(NO3)2, solution, add 5 cc. H2O, then a little HCl. No ppt. is formed. Now if a solution of AgNO3 and a solution of Cu(NO3)2 were mixed, and HCl added, it is evident that the silver would be precipitated as chloride of silver, while the copper would remain in solution. If now this be filtered, the silver will remain on the filter paper, while in the filtrate will be the copper. Thus we shall have performed an analysis, or separated one metal from another. Perform it. Note, however, that any soluble chloride, as NaCl, would produce the same result as HCl. BROMHYDRIC AND IODIHYDRIC ACIDS. 82. NaCl, being the most abundant compound of Cl, is the source of commercial HCl. KCl treated in the same way would give a like |
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