130996294-Group-2-Cations.pdf - Qualitative Analysis Group II Cations What are the Group 2 Cations Pb2 Hg2 Cu2 Bi3 Sb3 2 3 4 Cd As Sn GROUP 2

130996294-Group-2-Cations.pdf - Qualitative Analysis Group...

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Qualitative Analysis: Group II Cations
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What are the Group 2 Cations? Pb 2+ , Hg 2+, Cu 2+ , Bi 3+ , Sb 3+ , Cd 2+ , As 3+ , Sn 4+
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(Pb 2+ , Hg 2+, Cu 2+ , Bi 3+ , Sb 3+ , Cd 2+ , As 3+ , Sn 4+) …form S 2- precipitates that are insoluble in o.3M [H + ] solutions GROUP 2 CATIONS… …become precipitates in acidic solutions as insoluble sulfide salts can be separated from mixture by adding in acidic solution hydrogen sulfide, H 2 S, obtained from hydrolysis of thioacetamide, CH 3 CSNH 2 : CH 3 CSNH 2 + 2H 2 O H 2 S + CH 3 CO 2 - + NH 4
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Pb 2+ + H 2 S PbS + 2H + black Hg 2+ + H 2 S HgS + 2H + black Cu 2+ + H 2 S CuS + 2H + black Cd 2+ + H 2 S CdS + 2H + yellow 2Bi 3+ + 3H 2 S Bi 2 S 3 + 6H + dark brown / black 2As 3+ + 3H 2 S As 2 S 3 + 6H + yellow 3Sb 3+ + 3H 2 S Sb 2 S 3 + 6H + orange red Sn 4+ + 2H 2 S SnS 2 + 4H + yellow Group 2 Cations (sulfide salts)
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Group 2 Cations are further subdivided based on the reaction of their sulfide precipitate with excess S 2- . React with excess S 2- , form soluble complex sulfides Remain precipitates in presence of excess S 2- HgS As 2 S 3 Sb 2 S 3 SnS 2 PbS Bi 2 S 3 CdS CuS
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I. Group 2 Cations Precipitation
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  • Solubility, drops, Group II Cations, Cations Precipitation

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