Halides (AQA GCSE Chemistry)

• Acidify the sample with dilute nitric acid (HNO₃) followed by the addition of silver nitrate solution, AgNO₃
  • The acidification is done to remove carbonate ions that might give a false positive result

• If a halide is present it forms a silver halide precipitate:

Ag⁺ (aq) + X^– (aq) → AgX (s)

• Depending on the halide present, a different coloured precipitate is formed, allowing for identification of the halide ion
• Silver chloride is white, silver bromide is cream and silver iodide is yellow

Each silver halide produces a precipitate of a different colour