Question

How to obtain white precipitate from hydrogen chloride gas?

Answer 1

Preparation of precipitate from Hydrogen chloride gas

• Dilute Hydrogen chloride ($\mathrm{HCl}$) does not react with nitrates but can react with silver nitrate to form a white precipitate of silver chloride.
  $\underset{\mathrm{Hydrocholic}\mathrm{acid}}{\mathrm{HCl}(\mathrm{aq}.)}+\underset{\mathrm{Silver}\mathrm{nitrate}}{{\mathrm{AgNO}}_3(\mathrm{aq}.)}\to \underset{\mathrm{Silver}\mathrm{chloride}}{\mathrm{AgCl}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitric}\mathrm{acid}}{{\mathrm{HNO}}_3(\mathrm{aq}.)}$
• Hydrogen chloride ($\mathrm{HCl}$) is a colorless gas that forms white fumes of hydrochloric acid when brought into contact with atmospheric humidity.
• The Hydrogen and the Chlorine atom are connected by a covalent single bond.
• The covalent bond in between Hydrogen and Chlorine is highly polar since the chlorine atom is much more electronegative than the hydrogen atom.

Hence, to obtain white precipitate from hydrogen chloride gas there should be a reaction between $\mathrm{HCl}$ and ${\mathrm{AgNO}}_3$.