Question

How will you identify the HCl gas using silver nitrate solution? Give reactions involved.

Answer 1

When hydrogen chloride (HCl) gas is passed through a solution of silver nitrate (AgNO₃), a curdy white precipitate of silver chloride (AgCl) is formed.

To confirm the test, this white precipitate is treated with ammonium hydroxide (NH₄OH). The precipitate completely dissolves in excess ammonium hydroxide to form a clear, soluble complex.

\[ \text{AgNO}_3 + \text{HCl} \longrightarrow \text{AgCl}\downarrow\text{ (white ppt.)} + \text{HNO}_3 \]

\[ \text{AgCl} + 2\text{NH}_4\text{OH} \longrightarrow [\text{Ag(NH}_3)_2]\text{Cl}\text{ (soluble)} + 2\text{H}_2\text{O} \]