Chemistry - PRACTICAL ORGANIC CHEMISTRY Question with Solution | TestHub

For testing of halogens, Nitric acid is added to the sodium extract because if ${\mathrm{CN}}^{-}$ or ${\mathrm{S}}^{2-}$ are present then they will be oxidised and removed before the test of halides.

$\mathrm{NaCN}+{\mathrm{HNO}}_3\to {\mathrm{NaNO}}_3+\mathrm{HCN}\uparrow$
${\mathrm{Na}}_2\mathrm{S}+{\mathrm{HNO}}_3\to {\mathrm{NaNO}}_3+{\mathrm{H}}_2\mathrm{S}\uparrow$
Nilnic acid decomposed$\mathrm{NaCN} \& {\mathrm{Na}}_2\mathrm{S}$, else they precipitate in test & misquite the resolve