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JAMB Chemistry 1997 Question 35

Question 35

Qualitative Analysis

The reaction that occurs during the laboratory test for the presence of tetraoxosulphate (VI) ion is

  1. A.SO42−(aq) + Ba2+(aq) → BaSO4 (dil HNO3)
  2. B.Cu(s) + 4H+(aq) + 2SO42−(aq) → CuSO4(s) + 2H2O + SO2(g)
  3. C.4H+(aq) + 2SO42−(aq) + 2e− → SO42−(aq) + 2H2O(l) + SO2(g)
  4. D.CuO(s) + 2H+(aq) + SO4(aq) → CuSO4(aq) + H2O(l).
Show the answer and explanation

Answer: A (SO42−(aq) + Ba2+(aq) → BaSO4 (dil HNO3))

Explanation

The test for SO42− is to add a barium salt in dilute acid: a white precipitate of barium tetraoxosulphate(VI) forms.