Question

The presence of any of the halide ions i.e. chloride, bromide or iodide in a compound can be tested using _______ as a reagent.

• A. silver nitrate solution
• B. hydrogen sulfide
• C. sodium hydroxide
• D. ammonia solution

Answer 1

The correct option is A

silver nitrate solution

Explanation:

• In order to determine the presence of a halide, the solution is acidified with dilute Nitric acid (${\mathrm{HNO}}_3$).
• To this, a few drops of silver nitrate (${\mathrm{AgNO}}_3$) solution are added. The different colored precipitates of silver halide determines the halide ions present.
• For chloride $\left({\mathrm{Cl}}^{-}\right)$ ions, sodium chloride ($\mathrm{NaCl}$) reacts with silver nitrate (${\mathrm{AgNO}}_3$) and forms sodium nitrate (${\mathrm{NaNO}}_3$) and a white precipitate of silver chloride ($\mathrm{AgCl}$). The reaction is:

${\mathrm{AgNO}}_3\left(\mathrm{aq}\right)+\mathrm{NaCl}\left(\mathrm{aq}\right)\to {\mathrm{NaNO}}_3\left(\mathrm{aq}\right)+\mathrm{AgCl}\left(\mathrm{s}\right)$⇣

• For bromide $\left({\mathrm{Br}}^{-}\right)$ ions, sodium bromide ($\mathrm{NaBr}$) reacts with silver nitrate (${\mathrm{AgNO}}_3$) and forms sodium nitrate (${\mathrm{NaNO}}_3$) and a ream or off white precipitate of silver bromide$\left(\mathrm{AgBr}\right)$. The reaction is:

${\mathrm{AgNO}}_3\left(\mathrm{aq}\right)+\mathrm{NaBr}\left(\mathrm{aq}\right)\to {\mathrm{NaNO}}_3\left(\mathrm{aq}\right)+\mathrm{AgBr}\left(\mathrm{s}\right)$⇣

• For bromide $\left({\mathrm{I}}^{-}\right)$ ions, sodium iodide ($\mathrm{NaI}$) reacts with silver nitrate (${\mathrm{AgNO}}_3$) and forms sodium nitrate (${\mathrm{NaNO}}_3$) and a yellow precipitate of silver iodide $\left(\mathrm{AgI}\right)$. The reaction is:

${\mathrm{AgNO}}_3\left(\mathrm{aq}\right)+\mathrm{NaI}\left(\mathrm{aq}\right)\to {\mathrm{NaNO}}_3\left(\mathrm{aq}\right)+\mathrm{AgI}\left(\mathrm{s}\right)$⇣

Final Answer:

Hence, option (A) is correct. The presence of any of the halide ions i.e. chloride, bromide or iodide in a compound can be tested using silver nitrate solution as a reagent.