Question

The aqueous solution of potassium cyanide is mixed with aqueous solution of $Fe\left(\right.CN\left(\left.\right)_{2}$ . The resulting solution will give test for

• A. $K^{+}$ and $CN^{-}$ ions
• B. $K^{+},Fe^{2 +}$ and $CN^{-}$ ions
• C. $K^{+}$ and $\left[\right.Fe\left(\right.CN\left(\left.\right)_{6}\left(\left]\right.\right)^{3 -}$ ions
• D. $K^{+}$ and $\left[\right.Fe\left(\right.CN\left(\left.\right)_{6}\left(\left]\right.\right)^{4 -}$ ions

Answer 1

Answer: (D)

When an aqueous solution of potassium cyanide is mixed with aqueous solution of $Fe\left(\right.CN\left(\left.\right)_{2}$ , the resulting solution will give test for $K^{+}$ and $\left[\right.Fe\left(\right.CN\left(\left.\right)_{6}\left(\left]\right.\right)^{4 -}$ ions.
$4KCN+Fe\left(\right.CN\left(\left.\right)_{2} \rightarrow K_{4}\left[\right.Fe\left(\right.CN\left(\left.\right)_{6}\left]\right.\rightleftharpoons4K^{+}+\left[\right.Fe\left(\right.CN\left(\left.\right)_{6}\left(\left]\right.\right)^{4 -}$