Question:
The Lassaigne's extract is boiled with conc. $HNO_3$ while testing for halogens. By doing so it
The Lassaigne's extract is boiled with conc. $HNO_3$ while testing for halogens. By doing so it
Updated On: Jul 13, 2024
- helps in the precipitation of $AgCl$
- increases the solubility product of $AgCl$
- increases the concentration of $NO^-_3$ ions
- decomposes $Na_2S$ and $NaCN$, if formed
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The Correct Option is D
Solution and Explanation
Na$_2$S and NaCN, if present in the extract, will be
decomposed to H$_2$S and HCN by HNO$_3$ .
NaCN + HN$O_3$ $\rightarrow$ NaN$O_3$ + HCN
Na$_2$S + 2HNO$_3$ $\rightarrow$ 2NaN$O_3$ + H$_2$S
These will escape from the solution and will not
interfere with the test for halogens.
decomposed to H$_2$S and HCN by HNO$_3$ .
NaCN + HN$O_3$ $\rightarrow$ NaN$O_3$ + HCN
Na$_2$S + 2HNO$_3$ $\rightarrow$ 2NaN$O_3$ + H$_2$S
These will escape from the solution and will not
interfere with the test for halogens.
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