Organic Chemistry Some Basic Principles and Techniques - Result Question 53
####59. The Lassaigne’s extract is boiled with conc. $HNO_3$ while testing for halogens. By doing so it [2011]
(a) decomposes $Na_2 S$ and $NaCN$, if formed.
(b) helps in the precipitation of $AgCl$.
(c) increases the solubility product of $AgCl$.
(d) increases the concentration of $NO_3{ }^{-}$ions.
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Solution:
- (a) Conc. $HNO_3$ decomposes $NaCN$ and $Na_2 S$ to avoid their interference.
$ \begin{aligned} & NaCN+HNO_3 \longrightarrow NaNO_3+HCN \uparrow \\ & Na_2 S+2 HNO_3 \longrightarrow 2 NaNO_3+H_2 S \uparrow \end{aligned} $
