Consider a mixture 'X' which is made by dissolving 0.4 mol of [Co(NH3)5SO4]Br and 0.4 mol of [Co(NH3)5Br]SO4 in water to make 4 L of solution. When 2 L of mixture 'X' is allowed to react with excess of AgNO3, it forms precipitate 'Y'. The rest 2 L of mixture 'X' reacts with excess BaCl2 to form precipitate 'Z'. Which of the following statements is CORRECT?
- 0.1 mol of 'Y' is formed.
- 0.4 mol of 'Z' is formed.
- 0.2 mol of 'Z' is formed.
- 'Y' is BaSO4 and 'Z' is AgBr.
Answer
(3) 0.2 mol of 'Z' is formed.
Solution
Each 2 L portion contains 0.2 mol of each complex.
Ions in solution:
[Co(NH3)5SO4]Br [Co(NH3)5SO4]+ + Br- (only Br- is free)
[Co(NH3)5Br]SO4 [Co(NH3)5Br]2+ + SO42- (only SO42- is free)
With excess AgNO3: Ag+ + Br- AgBr Y = AgBr, 0.2 mol
With excess BaCl2: Ba2+ + SO42- BaSO4 Z = BaSO4, 0.2 mol
(Ligands inside the coordination sphere are not precipitated.)
0.2 mol of 'Z' is formed.
Answer: (3)