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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    CHLORIDE OF AMMONICM TOGETHEE WITH SULPHIDE. Fe,Cle + 6NH4OH = 6NH4C1 + Fe2O0H5. A1.C1, + 6NH4OH = 6NH,C1 + AUOUH0. Cr.;3S04 + 6NH4OH = 3[(NH4)2S04] + Cr2O0Ha. Group III.—No precipitate: absence of Ferric, Aluminum and Chromic salts, soluble in water. Pass on to Group IV. Division A. Group 1V.—The metals of this Group are not pre- cipitated by Hydric chloride HC1: nor by Hydric sulphide H2S, in presence of Hydric chloride HC1: nor by Amnionic hydrate NH4OH, in presence of Ammonic chloride NH4C1. To a fresh portion of the Original Solution, Ammonium chloride is added, and then Ammonium sulphide. The latter test is similar in its reaction to Hydric sulphide in Group-test II., and, if used by itself would first precipitate all the metals of Groups I., II., III., and IV. It should never be added to an acid solution, as the Acid decomposes the Ammonium sulphide: for this reason, we neutralize an acid solution with Ammonium hydrate, before addition of Ammonium sulphide. Solutions of Salts of Ferrous, Cobalt and Nickel, Zinc and Manganous belong to this Group IV., and are pre- cipitated as foilphides, insoluble both in water and in the tests. FeS04 + (NH.)oS = (NH4)2S04 + FeS, black. CoCl2 + (NH4),S = 2NH4C1 + CoS, black. NiCI2 + (NH4)~S = 2NH4Cl + NiS, black. MnS04 + (NH,)2S = (NH412S04 + MnS, flesh-coloured. ZnS04 + (NH4;2S = (NH4)2S04 + ZnS, white. Group IV.—No precipitate: absence of soluble salts of Ferrous, Cobalt and Nickel, of Manganous and of Zinc. Division A. Group V.—The Metals of this Group are not pre- cipitated by Hydric chloride HOI: nor by Hydric sulphide H2S, in presence of Hydric chloride HC1: nor by Ammonic hydrate NH4OH, in presence of Ammonic chloride NH4C1: nor by Ammonic sulphide (NILJjjS, in presence of Ammonic chloride NH4C1. To a fresh portion Ammonic chloride is added, and then, drop- wise, Ammonic carbonate. a. A white precipitate of, respectively, Barium carbonate, Stron- tium carbonate, and Calcium carbonate, from any soluble salt of Barium, Strontium and Calcium. BaCl2 + (NH.,)2C08 = 2NH4C1 + BaC03, white. SrCl2 + (NH()2C03 = 2NH..CI + SrCOa, white. CaCla + (NH4)2C08 = 2NH4C1 + CaCOa, white. Group V.—a, No precipitate: absence of soluble salts of Barium, Strontium and Calcium. b. No precipitate, but only by Sodic carbonate Na2C03, the Divisional-test A : Magnesium is present in form of some soluble