Notes on analytical chemistry for students in medicine : extracted from the fifth edition of "Notes for students in chemistry" / by Albert J. Bernays.

  • Albert Bernays
Date:
1889
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Licence: Public Domain Mark

Credit: Notes on analytical chemistry for students in medicine : extracted from the fifth edition of "Notes for students in chemistry" / by Albert J. Bernays. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    LEAD AND CTJPKIC SULPHIDES INSOLUBLE. yellow color, as Platinic chloride is really 2HCl,PtCl4. Excess of KHO gives the yellow Hydrate when boiled. NH4HO, gives yellow precipitate of 2NH4Cl,PtCl4, because the Ammonia finds the necessary HC1 to make it Amnionic chloride. Oxalic acid does not reduce Platinic salts. On Charcoal, heated in the blow-pipe flame, Platinum remains as an in- fusible grey powder, flattened under pestle, in mortar, to dull white metal. b. Sulphides insoluble in Ammonic sulphide, after neutral- ising free acid with Ammonic hydrate. Lead, Plumbum, Pb = 207. Chief salts : acetate, nitrate, chloride, See p. 16. In a dilute solution of a Lead-salt, although Na2C03 will have given a white precipitate, HC1 will occasion none: Lead oxide must be sought for again in Group II., sub- division b, by the same tests as already given at p. ] 6. 9. Copper, Cuprum, Cu = 63-3. A lustrous metal of red color, malleable, ductile, and tenacious. Dyad. Sp. gr. 8-95. Sp. heat 0-093. Melts at 1300°. Oxydizes readily at a red- heat, forming both red Cuprous oxide and black Cupric oxide. Sometimes native. Insoluble in dilute Sulphuric and Hydrochloric acids: slowly soluble in HC1 in presence of air: Cu + 2HC1 = CuCL + H2. With hot Sulphuric acid: Cu + 2H2S04 = CuS04 + 2H20 + S02. With dilute JNitric acid: 3Cu + 8HN03 - 3(Cu2N03) + 4H20 + 2NO. A good method of making Nitric oxide. Chlorine attacks it immediately; to Cupric chloride, CuCl2. Cupric oxide, CuO, is the chief Oxide. Eeadily prepared by heating Cupric nitrate, Cu2N03, to redness. It is black and quite insoluble in water. With 2HC1, into green CuCl2 and H20. With Nitric acid, into blue Cu2N03, and H20. With H2S04, into CuS04 and H20. Anhydrous Cupric sulphate is white ; blue vitriol, CuS04,5H20, blue crystals. Cuprous oxide, Cu20, is Euby Copper Ore : salts colorless. The chief ore of copper is Copper pyrites, FeCuS2. By roasting, the Iron oxydized, and slagged off as Silicate by further heating with Silica, Si02. Sulphur dioxide is given off, and on further calcining the Cuprous sulphide, Cu2S, it becomes in part 2CuO + SO„. When 2CuO is heated with remaining Cu„S, we obtain 4Cu + S02. Tests for Cvpric in soluble salts. The commonest are the sulphate, nitrate, chloride, and acetate. All are colored blue or green, and have an acid reaction. The color of the solution would suggest either a Cupric or a Nickel salt. Na2COs, blue precipitate of basic carbonate, soluble with deep- blue color in NH,OH. Malachite is CuH202,CuC03: it is green. Azurite is 2CuH202 CuC03, and is blue. II. HC1 + H2S brown-black ppt. of Cupric sulphide CuS, slightly coloring the solution. Insoluble in Ammonic sulphide. HC1 alone, changes blue solution to green. KOH, blue precipitate of CuH202. insoluble in excess: when heated, in part into biack CuO. If glucose first added, CuH202 is