Detection of Halogens

Acidify sodium extract with conc. $$\text{HNO}_3$$ (to boil off $$\text{HCN}$$ and $$\text{H}_2\text{S}$$) and add $$\text{AgNO}_3$$ solution:

• Chlorine ($$\text{Cl}$$): White precipitate ($$\text{AgCl}$$), soluble in ammonium hydroxide ($$\text{NH}_4\text{OH}$$).
• Bromine ($$\text{Br}$$): Pale Yellow precipitate ($$\text{AgBr}$$), sparingly soluble in $$\text{NH}_4\text{OH}$$.
• Iodine ($$\text{I}$$): Bright Yellow precipitate ($$\text{AgI}$$), completely insoluble in $$\text{NH}_4\text{OH}$$.