Qualitative Analysis - Result Question 64
####67. A light bluish green crystalline compound responds to the following tests
(i) Its aqueous solution gives a brown precipitate or colouration with $K _2\left[HgI _4\right]$.
(ii) Its aqueous solution gives a blue colour with $K _3\left[Fe(CN) _6\right]$.
(iii) Its solution in hydrochloric acid gives a white precipitate with $BaCl _2$.
Identify the ions present and suggest the formula of the compound.
(1992, 4M)
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Solution:
- (i) Brown precipitate or colour with $K _2 HgI _4$, indicates the presence of $NH _4^{+}$ion.
(ii) Aqueous $Fe(II)$ solution gives a blue colour with $K _3\left[Fe(CN) _6\right]$ due to formation of $Fe\left[Fe(CN) _6\right\rceil$ ion :
$$ Fe^{2+}+Fe(CN) _6^{3-} \longrightarrow \underset{\text { Blue colouration }}{Fe\left[Fe(CN) _6\right]} $$
(iii) Aqueous solution of $SO _4^{2-}$ ion in $HCl$ gives white ppt with $BaCl _2$ solution.
$$ SO _4^{2-}+BaCl _2 \longrightarrow BaSO _4 \downarrow+2 Cl^{-} $$
