Which of the following statement(s) is/are correct regarding group V cations?
A
The Group V cations are precipitated as their carbonates which dissolve in acetic acid due to the formation of corresponding acetates.
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B
Ba2+ ions have a grassy green coloured flame.
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C
Sr2+ ions have a crimson coloured flame.
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D
All of the above.
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Solution
The correct option is D All of the above. Take original solution and add small amount of solid NH4Cl and an excess of NH4OH solution followed by solid ammonium carbonate (NH4)2CO3
White precipitate indicates the presence of group V cations
The Group–V cations are precipitated as their carbonates which dissolve in acetic acid due to the formation of corresponding acetates.
Test for Ba2+ Ions:
Potassium chromate (K2CrO4) solution gives a yellow precipitate of barium chromate when the solution of fifth group precipitate in acetic acid is treated with it. BaCO3+2CH3COOH→(CH3COO)2Ba+H2O+CO2
(CH3COO)2Ba+K2CrO4→BaCrO4Barium chromate(yellow precipitate)+2CH3COOK
A grassy green colour of the flame confirms the presence of Ba2+ions.
Test for Sr2+ Ions
Ammonium sulphate (NH4)2SO4 solution gives a white precipitate of Strontium sulphate when the solution of fifth group precipitate in acetic acid is treated with it. SrCO3+2CH3COOH→(CH3COO)2Sr+H2O+CO2
(CH3COO)2Sr+(NH4)2SO4→SrSO4Strontium sulphate(white precipitate)+2CH3COONH4
A crimson red flame confirms the presence of Sr2+ions.
Test for Ca2+ Ions:
Solution of the fifth group precipitate in acetic acid gives a white precipitate with ammonium oxalate solution CaCO3+2CH3COOH→(CH3COO)2Ca+H2O+CO2