1. Tardigrade
  2. Question
  3. Chemistry
  4. A light bluish green crystalline compound responds to the following tests (i) Its aqueous solution gives a brown precipitate or colouration with K2 [HgI4]. (ii) Its aqueous solution gives a blue colour with K3[Fe(CN)6]. (iii) Its solution in hydrochloric acid gives a white precipitate with BaCl2. Identify the ions present and suggest the formula of the compound.

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Q. A light bluish green crystalline compound responds to the following tests
(i) Its aqueous solution gives a brown precipitate or colouration with $K_2 [HgI_4]$.
(ii) Its aqueous solution gives a blue colour with $K_3[Fe(CN)_6]$.
(iii) Its solution in hydrochloric acid gives a white precipitate with $BaCl_2.$
Identify the ions present and suggest the formula of the compound.

IIT JEEIIT JEE 1992Organic Chemistry – Some Basic Principles and Techniques

Solution:

(i) Brown precipitate or colour with $K_2 HgI_4$, indicates the presence of $NH_4^+$ ion.
(ii) Aqueous $Fe(ll)$ solution gives a blue colour with
$K_3 [Fe(CN)_6]$ due to formation of $Fe[Fe(CN)_6]^- $ ion :
$ Fe^{2+} + Fe(CN)_6^{3-} \longrightarrow \, \underset {\text{Blue colouration}}{Fe[Fe(CN)_6]^-}$
(iii) Aqueous solution of $SO_4^{2-}$ ion in $HCl$ gives white ppt with $BaCl_2$ solution
$ SO_4^{2-} + BaCl_2 \longrightarrow BaSO_4 \downarrow + 2Cl^-$