SCH4C  Qualitative Analysis - Group 4 Analysis Separation Table
                                            The Alkaline Earth Group
To the group 4 precipitate add 4 mL of acetic acid and 4 mL of (NH4)2CO3.  Agitate to dissolve the precipitate (reaction #28)
Add 2 mL of K2CrO4 until the precipitate appears to be complete.  Filter if necessary (reaction 29a)
Precipiate:  BaCrO4
Add enough HCl to redissolve the BaCrO4.  Add H2SO4 drop by drop.  A white precipitate of BaSO4 confirms the presnece of Ba2+.
(reaction #29b)
Filtrate:  Sr2+ and Ca2+
Add 2 mL of dilute H2SO4.  Filter if necessary.  (reaction #30)
Precipitate:  SrSO4
A white precipitate confirms the presence of Sr2+
Filtrate:   Ca2+
Add NH4OH to neutralize the sulphuric acid.  Add potassium oxalate (K2C2O4) to produce CaC2O4 if Ca2+ is present.  A white precipitate at this point confirms Ca2+.

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