Qualitative Analysis of Calcium Ion

A pinch of NH₄Cl is added to original solution. On adding excess of NH₄OH to make the solution alkaline then add freshly prepared (NH₄)₂CO₃ solution, a white precipitate is obtained.

Ca²⁺ + CO₃^2- → CaCO₃

Confirmatory Test

White precipitate is soluble in acetic acid.

CaCO₃ + 2CH₃COOH → Ca(CH₃COO)₂ + H₂O

A white precipitate of calcium oxalate is formed on adding ammonium oxalate to above solution.

Ca(CH₃COO)₂ + (NH₄)₂C₂O₄ → CaC₂O₄