Identifying Cations - Test with Sulphate Ions

  1. Out of the 10 cations, only calcium ions and lead(II) ions will form a precipitate with sulphate ions.
  2. This is because both calcium sulphate and lead(II) sulphate are insoluble in water.
  3. The chemical reaction is a double decomposition reaction.
    Pb2+ + SO42- → PbSO4
    Ca2+ + SO42- → CaSO4


H2SO4 or Na2SO4
Na+
-
Ca2+
White precipitate.
Mg2+
-
Al3+
-
Zn2+
-
Pb2+
White precipitate.
Fe2+
-
Fe3+
-
Cu2+
-
NH4+
-

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