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Group I Cations A INTRODUCTION Most metal halides are soluble in water and dilute hydrochloric acid. The exceptions are silver ion, Ag mercurous ion, Hg,: and lead(II) ion, Pb. Consequently, the addition of HCI to a solution of metal cations leads to the selective precipitation of these three ions. While the theory behind the separation and identification of these ions has been outlined in the general discus- sion of the qualitative analysis scheme, some aspects of this chemistry need to be highlighted. AgCl, PbCl2, and Hg,Cl2 are all white solids. The Pb ions have the greatest solubility of the three ions in the presence of chloride. PbCl, is appreciably soluble in hot water; while in con- centrated HCI, the salt reacts to form soluble [PbCl The following procedures must be fol- lowed carefully to guarantee that Pb2 is trapped as the solid chloride salt Hg,Cl, is unstable in the presence of base. Under these conditions, the two Hg0) ions of Hg-Cl2 disproportionate to form an atom of Hg and a mercuric ion, Hg, The appearance of dark drop- lets of metallic mercury confirms the presence of mercury. Note that with the use of ammonia to raise the pH, the Hg ions react to form the white solid HgCINH2. Thus, the product formed is a mixture of droplets of liquid mercury metal and a white solid of HgCINH2, and the mixture can have a variable appearance from gray to dark gray depending on the size of the droplets and the particles of solid. Finaily, the presence of silver ions is determined based on whether a white solid of silver chloride forms upon acidification of the solid remaining after the precipitation of mercury and HacINH2. Note that the acidification is accomplished with nitric acid rather than HCl. The chlo ride necessary for the precipitation of silver ions is already present from the initial removal of the Group I metal cations by the addition of HCl. SAFETY NOTES: Safety goggles and gloves will be required for all steps of the laboratory. Hydrochloric acid and nitric acid are strong acids and should be handled carefully. Spills should be cleaned up immediately. If contact is made with your skin, rinse thoroughly with water. Chromate compounds are carcinogenic whi with the K2CrO4 solution. inhaled; care should be taken to avoid contact Unwanted chemicals are not to go down the sink. They are to be put in a designated container. See your instructor for disposal instructions. EXPERIMENTAL PROCEDURES Step 1. Removal of Pb2, Ag, and Hg22 Obtain 1 to 2 mL of the solution of unknown cations. If you must choose from multiple unknown solutions, record the number of your unknown. To the solution of unknown cations, add 10 drops From Chapter 27A of Laboratory Manual for Chenistry: A Molecalar Approack, Fourth Edition, Nivaldo J. Trm Aohn B. Vincent and Erica Livingston. Copyright O 2017 by Pearson Education, Inc. All rights reserved Copyright© 2017 Pearson Education, Inc.

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Confirmation Text of iron Iven may be Confirmed by KENS, kg[fe(CN)6] and Ku[fe(CN) easily as given in ferrous and terrie ion Test ahead Example (Reaction) reation of fest f3+ + 3 [Fe (CN) 674 – feq[fe(ng] = on from Ku (felor) Keussian's Blue Thank hope this will help you Good luck MAXX