Notes on analytical chemistry : for students in medicine / by Albert J. Bernays.

  • Albert Bernays
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: Notes on analytical chemistry : for students in medicine / by Albert J. Bernays. Source: Wellcome Collection.

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    Group-Test II.—HCl + H,S. 13. Palladium, Pd = 106. Lvistroas metal, silver-white. Unchangeable in air. Sp.gr. 11-4. Pre- cipitated from palladous chloride by potassium iodide, and from the latter by heat. Dissolved by hot nitric acid, and by sulphuric acid: slowly by hydrochloric acid. Palladous oxide PdO is black: prepared by heating Pd2NO3. Solutions of salts, brown or reddish-brown. Tests for palladous in soluble salts : chloride, nitrate, or sulphate. II. HCl-fHjS precipitates black palladous sulphide, insoluble in ammonium sulphide, but soluble in boiling HCl. KOH, brown basic salt, soluble when boiled. NH4OH, flesh-colored precipitate, soluble in excess. KI, black palladous iodide. FeSO^, precipitates palladium as a black powder. Heated on charcoal, the salts yield spongy palladium. 14. Iron as Ferric. Ferric salts are yellow, yellow-red, or red-brown. Acid reaction. Sodimn carbonate, with effervescence, a bulky red precipitate. HCl deepens the yellow or yellow-red color II. HCl-fHjS reduces ferric salts to ferrous, Group IV. Only sulphur, of white, or yellow color is deposited. Thus :— Fe„Cl6-i-HCl-l-H,S = 2FeClj-|-S-l-2HCl+HCI. If then a whitish or yellowish precipitate in a solution originally colored reddish-yellow or yellow, add NH4OH to one portion : this, with the HjS present, forms ammonium sulphide, and throws down black hydrated ferrous sulphide. To another portion of the HCI + H2S reaction, add potassium ferricyanide ; Turnbull's blue is precipitated. A ferric salt was present. See Group III. N.B. HCl+H^S reduces solutions of chromic acid of rich red-yellaw color to the condition of green salts of chromic oxide. See chromic acid, p. 44. Chromates of the alkaline metals soluble in water. The acid chro- mates, of red-yellow color, with effervescence, into neutral yellow chromates, by sodium carbonate. Group 7/7.—From soluble salts, the metals of this group are not precipitated either as chlorides or as sulphides. To the tests HCl + H2S float a few drops of ammonic hydrate: if no precipitate, pass on to Group V. If a precipitate, the only metal in Group III., which would be as black ferrous sulphide, is ferric; aluminum would be white; chromic would be dirty green. The metals of this Group III. are precipitated as hydroxides in neutral solutions to which first ammonium chloride, and then ammonia has been added. Comprises : Ferric as hydroxide . FeaHgOg. Manganic as hydroxide . Mn2H606. Aluminum as hydroxide A12U606-
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