CHEM 1&2 Lab Manual & worksheets pg 197

CHEM 1&2 Lab Manual & worksheets pg 197 -...

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Experiment 19: Qualitative Analysis General Chemistry I and II Lab Manual Dakota State University page 197 of 232 Add dilute sulfuric acid to one portion the above decantate; the formation of a precipitate verifies the presence of lead. Notice that you should regard lead as present if it shows positive in EITHER group I or group II (or, naturally, in both). Verification of Bi +3 : Add ammonium hydroxide to the second portion of the above decantate until the solution is alkaline according to litmus paper. Formation of a precipitate is verification of the presence of bismuth. Verification of Cu +2 : Add concentrated ammonium hydroxide dropwise to the final portion. If a precipitate forms, continue adding ammonium hydroxide until it dissolves. A blue color of the solution is a verification of copper.
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Unformatted text preview: Group III: Group III ions precipitate as sulfide ions, just as group II, except in an alkaline solution rather than acidic. These ions (Ni +2 , Co +2 , Mn +2 , Al +3 , and Cr +3 ; many qualitative analysis schemes include Fe +3 and Zn +2 in group III) precipitate on the addtion of ammonium sulfide, leaving behind groups IV and V. Separation of group III ions from groups IV and V: Heat the decantate from group II in a hot water bath to reduce the volume to CoNO2 NiDMG Ni+2 DMG Ni+2,Co+2 KNO2 MnO4-Mn(OH)2 KClO3 AlAluminon AlOH HCl,Aluminon CrO4-2 Cr+3 Na2O Al+3,Cr+3 HNO3,NH4OH Mn+2,Al+3,Cr+3 NaOH MnS,Al2S3,Cr2S3 Aqua Regia NiS,CoS,MnS,Al2S3,Cr2S3 HCl Groups IV and V Ni+2,Co+2,Mn+2,Al+3,Cr+3,group IV and V NH4OH,Na2S...
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This note was uploaded on 01/27/2012 for the course CHM 2045 taught by Professor Josephwalter during the Fall '11 term at Dakota State.

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