JEE Main · 2021 · 27 Aug 2021 · Shift 1 · Coordination Compounds

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Acidic ferric chloride solution on treatment with excess of potassium ferrocyanide gives a Prussian blue coloured colloidal species. It is:

(A) $KFe [Fe (CN)_{6}]$ ✓ Correct
(B) $K_{5} Fe [Fe (CN)_{6}]_{2}$
(C) $Fe_{4} [Fe (CN)_{6}]_{3}$
(D) $HFe [Fe (CN)_{6}]$

Answer: (A)

Solution

With excess potassium ferrocyanide the ferric ions are the limiting species, and the soluble, colloidal form of Prussian blue is produced, with potassium ions balancing the charge. This species contains

F e^{3 +}

and

[Fe (CN)_{6}]^{4 -}

and has the formula

KFe [Fe (CN)_{6}]

. The colloidal Prussian blue formed is

KFe [Fe (CN)_{6}]

JEE Main · 2021 · 27 Aug 2021 · Shift 1 · Single correct option

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