Sabrina Walters 3/22/17 CHM 127 Professor Beaton The Chemistry and Qualitative Analysis of Cations: Group II The purpose behind this lab was to determine what group two cations were in a known solution. We are to use the chemistry of these ions to establish a procedure for verifying qualitatively the presence of these selected cations. The principle theory is that through centrifugation and the addition of strong acids and bases, you can determine what ions are present in a solution. First, obtain a solution containing four known cations. The solution should have ten drops of 1M thioacetamide to the solution and heat it for ten minutes, cool it, and then add one drop of 0.5M NH 3 . Centrifuge for two minutes, add five more drops of 1M thioacetamide, heat for another two minutes in a boiling water bath, cool it, then add another drop of 0.5M NH 3 . Centrifuge the new solution for two minutes and discard the supernatant liquid produced. Add 0.1M NH 4 Cl to the residue and centrifuge the solution for another two minutes. Discard of the supernatant liquid and assume that the residue left over contains Bi 2 S 3 , CdS, CuS, and SnS 2 . Add 20 drops KOH, one drop of 1M thioacetamide, and heat the new solution for two minutes in a boiling water bath. Centrifuge for two minutes and test the supernatant liquid to decide if it is Sn(OH) 6 2- . Add 6M HCl to make the solution acidic and test with short range alkacid paper, add five drops of 1M thioacetamide, and then heat for two minutes in a boiling water bath, and
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- Spring '16
- Chemistry, supernatant liquid