The Group IV cations are Ba2+, Sr2+, Ca2+. These metals form chlorides, sulfides and hydroxides that are soluble under that prevail in the precipitations of Group I, II, and III.

1. Jessa S. Ariño
BSE-4B
Central Bicol State University of
Agriculture
ANALYSIS OF GROUP IV
CATIONS

2. Group Separations in Qualitative
Analysis

3. Group Separations in Qualitative
Analysis

6. Precipitation of Group 4-Cations
• The Group IV cations are Ba2+, Sr2+, Ca2+.
• These metals form chlorides, sulfides and
hydroxides that are soluble under that
prevail in the precipitations of Group I, II,
and III.

7. • The carbonates of barium, strontium,
and calcium precipitate in aqueous
ammonia solutions containing
ammonium carbonate.
• These conditions give a carbonate
concentration high enough to precipitate
BaCO3, SrCO3, and CaCO3 but not MgCO3.

8. • To bring the solution to the required
ammonium concentration, the
centrifugate from Group III separation,
which contains ammonium salts, is first
evaporated to dryness and then heated
strongly to expel the ammonium salts
present. The equations are:
NH4Cl NH3(g) + HCl(g)
NH4NO3 N2O(g) + 2H2O(g)

9. • The necessary ammonium ion
concentration is then obtained by adding
the group IV precipitant, which consists
of ammonium chloride and aqueous
ammonia in the required concentrations.
Ba2+ + CO3
2 BaCO3 (white)
Sr2+ + CO3
2 SrCO3 (white)
Ca2+ + CO3
2 CaCO3 (white)

10. BARIUM

11. SEPARATION and IDENTIFICATION
of BARIUM
1. Dissolution of the Carbonates
BaCO3 + 2CH3CO2H Ba2+ + 2CH3CO2 + H2O + CO2
2. Separation of Barium from Strontium
and Calcium
Cr2O7
2 + H2O 2CrO4 + 2H+
3. Dissolution of Barium Chromate
- A solution of 12M HCl is used to bring about the
dissolution of BaCrO4

12. 3. Dissolution of Barium Chromate
- A solution of 12M HCl is used to bring about the
dissolution of BaCrO4
4. Identification of Barium
- the presence of barium ion in the solution is confirmed
by precipitating it as barium sulfate, using sulfuric acid as
the precipitant.
- flame test- yellow green color

13. STRONTIUM

14. SEPARATION and IDENTIFICATION
of STRONTIUM
1. Separation of Strontium from Calcium
Cr2O7
2 + 2NH3 + H2O 2CrO4
2 + 2NH4
+
2. Identification of Strontium
- the formation of a fine yellow crystalline precipitate of
strontium chromate confirms the presence of strontium
- flame test- crimson color

15. CALCIUM

16. IDENTIFICATION of CALCIUM
• The solution from the strontium chromate
separation contains the calcium ion.
• The addition of ammonium oxalate precipitates
calcium oxalate, CaCrO4, a white crystalline salt.
Ca2+ + C2O4
2 CaC2O4
• Flame test- brick red color

17. THANK YOU!!!
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