Extraction of Metals - Result Question 29
29. In the process of extraction of gold,
Roasted gold ore $+CN^{-}+H _2 O \xrightarrow{O _2}[X]+HO$
$ [X]+Zn \longrightarrow[Y]+Au $
Identify the complexes $[X]$ and $[Y]$.
$(2003,1 M)$
(a) $X=\left[Au(CN) _2\right]^{-}, \quad Y=\left[Zn(CN) _4\right]^{2-}$
(b) $X=\left[Au(CN) _4\right]^{3-}, Y=\left[Zn(CN) _4\right]^{2-}$
(c) $X=\left[Au(CN) _2\right]^{-}, Y=\left[Zn(CN) _6\right]^{4-}$
(d) $X=\left[Au(CN) _4\right]^{-}, Y=\left[Zn(CN) _4\right]^{2-}$
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Answer:
Correct Answer: 29. (a)
Solution:
$\mathrm{Au}+2 \mathrm{CN}^{-} \longrightarrow \underset{X} {[\mathrm{Au}(\mathrm{CN})_2]^{-} } $
$ 2 \mathrm{Au}(\mathrm{CN})_2^{-}+\mathrm{Zn} \longrightarrow \underset {Y}{[\mathrm{Zn}(\mathrm{CN})_4]^{2-}} +2 \mathrm{Au} $
BETA
