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An aqueous solution of a salt containing a cation Z^ n+ reacts with potassium hexacyanoferrate(II) solution to yield a characteristic Prussian blue precipitate. The identity of the cation Z^ n+ and the chemical formula of the Prussian blue precipitate are respectively:

Options

  1. AFe²⁺ and Fe₃[Fe(CN)₆]₂
  2. BCu²⁺ and Cu₂[Fe(CN)₆]
  3. CFe³⁺ and Fe[Fe(CN)₆]
  4. DFe³⁺ and Fe₄[Fe(CN)₆]₃

Correct answer

D. Fe³⁺ and Fe₄[Fe(CN)₆]₃

Step-by-step solution

In the qualitative analysis of Group III cations, the Fe³⁺ ion reacts with potassium hexacyanoferrate(II), K₄[Fe(CN)₆] , to form a characteristic Prussian blue precipitate. The chemical reaction is given by: 4Fe³⁺ + 3K₄[Fe(CN)₆] Fe₄[Fe(CN)₆]₃ + 12K⁺ The Prussian blue precipitate is Iron(III) hexacyanoferrate(II), which has the formula Fe₄[Fe(CN)₆]₃ . Answer: Fe³⁺ and Fe₄[Fe(CN)₆]₃

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