The reaction of K 3 [ Fe ( CN ) 6 ] with freshly prepared FeSO 4 solution produces a dark blue precipitate called Turnbull's blue. Reaction of K 4 [ Fe ( CN ) 6 ] with the FeSO 4 solution in complete absence of air produces a white precipitate X , which turns blue in air. Mixing the FeSO 4 solution with NaNO 3 , followed by a slow addition of concentrated H 2 SO 4 through the side of the test tube produces a brown ring. Precipitate X is

Chemistry · Practical Inorganic chemistry (Qualitative Analysis)

JEE Advanced 2021 — Paper 2 — Question 41

The reaction of $\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$ with freshly prepared $\mathrm{FeSO}_{4}$ solution produces a dark blue precipitate called Turnbull's blue. Reaction of $\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$ with the $\mathrm{FeSO}_{4}$ solution in complete absence of air produces a white precipitate $\mathbf{X}$ , which turns blue in air. Mixing the $\mathrm{FeSO}_{4}$ solution with $\mathrm{NaNO}_{3}$ , followed by a slow addition of concentrated $\mathrm{H}_{2} \mathrm{SO}_{4}$ through the side of the test tube produces a brown ring.

Precipitate $\mathbf{X}$ is

Option A:
$\mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3}$
Option B:
$\mathrm{Fe}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$
Option C:
$\mathrm{K}_{2} \mathrm{Fe}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$
Correct
Option D:
$\operatorname{KFe}\left[\operatorname{Fe}(\mathrm{CN})_{6}\right]$

Answer: C

Step-by-step solution

\mathrm{FeSO}_{4}+\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right] \longrightarrow \mathrm{K}_{2} \mathrm{Fe}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]

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Exam: JEE Advanced 2021
Paper: Paper 2
Subject: Chemistry
Chapter: Practical Inorganic chemistry (Qualitative Analysis)
Topic: Other Misc Reactions/ Tests

The reaction of K 3 [ Fe( CN) 6 ] with freshly prepared FeSO 4 solution produces a dark blue precipitate called Turnbull's blue. Reaction…

Answer: C

Step-by-step solution

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