SCH4C                                     Introduction to Qualitative Analysis

Initial Groupings of the Ions in Table Form

The division of the 21 catiosn into 5 smaller groups has been summarized below.
 
 
Start Here ---> To the unknown solution add dilute HCl (possible ions of all 5 groups)
precipitate:
AgCl  white
Hg2Cl2  grey
PbCl2 white

Group 1:
The Silver
Group

filtrate: (possible ions of Groups 2 to 5)
Adjust pH to 2  and add H2S gas
precipitate:
CuS  brown
PbS  brown
Bi2S3  brown
HgS  black
CdS   yellow

Group 2:
The Sulphide 
Group
 

filtrate: (possible ions of Groups 3 to 5)
Adjust pH to 7 and above, add more H2S gas.
precipitate:
Al(OH)3    white
Cr(OH)3  green
FeS   brown
Fe2S  brown
MnS   flesh
ZnS   white
CuS   black
NiS black

Group 3:
The Ammonium
Sulphide Group

 

filtrate:  Groups 4 and 5
Add NH4OH and (NH4)2CO3
precipitate:
BaCO3  white
CaCO3  white
SrCO3   white
MgCO3   white

Group 4:
The Alkali
Earth Group
 

filtrate:
Na1+ and K1+

Group 5:
The Alkali Group


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Copyright 1997, 2002, 2003  Tom Stretton (stretton@ripnet.com) Updated August, 2002 ts.