When small amount of ammonia is added to CUSO4 solution in water, blue PPt of [Cu(H2O)4(OH)2] is formed. The blue PPt dissolves on addition of excess of ammonia. The product formed is:
Correct answer: C. [Cu (NH3)4 (H2O)2]2+
- A. [Cu(H2O)2 (NH3)2 (OH)2]
- B. [Cu(NH3)4 (OH)2]
- C. [Cu (NH3)4 (H2O)2]2+
- D. [Cu (NH3)3 (H2O)3]2+
Explanation
Ammonia acts as a ligand in this reaction, replacing water molecules in the coordination sphere of the copper ion, forming [Cu(NH3)4(H2O)2]2+, a complex ion known as tetraamminediaquacopper (II). The ammonia molecules do not act as hydroxides in this context, hence options B and D are incorrect. Option A is incorrect due to the wrong ligand arrangement. The correct complex is stable and soluble, explaining the dissolution of the blue precipitate.
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The electronic structure of d-block elements covers the filling of the (n-1)d and ns orbitals, general electronic configurations, and the exceptions shown by chromium and copper. It explains how partially filled d orbitals produce variable oxidation states, coloured ions, magnetic behaviour and complex formation, while distinguishing transition elements from elements with completely filled d subshells.
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