In Carius method, halogen containing organic compound

Organic compound is heated with fuming nitric acid in the presence of silver nitrate in carius method.

Lunar caustic $\left(\mathrm{AgNO}_{3}\right)$ is used as reagent hare to

distinguish $\mathrm{Cl}^{-}, \mathrm{Br}$ and $\mathrm{I}^{-}$respectively as follows.

$\mathrm{Cl}^{-}(\mathrm{aq}) \stackrel{\mathrm{AgNO}_{3}}{\longrightarrow} \mathrm{AgCl} \downarrow_{\mathrm{ppt}}$ white

$\mathrm{Br}^{-}(\mathrm{aq}) \stackrel{\mathrm{AgNO}_{3}}{\longrightarrow} \mathrm{AgBr} \downarrow_{\mathrm{ppt}}$ pale yellow

$\mathrm{I}^{-}(\mathrm{aq}) \stackrel{\mathrm{AgNO}_{3}}{\longrightarrow} \mathrm{AgI} \downarrow_{\mathrm{ppt}}$ Dark yellow