AQA GCSE Chemistry

Revision Notes

8.3.4 Halides

Silver Nitrate Test

  • 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

The-silver-halide-precipitates, IGCSE & GCSE Chemistry revision notes

Each silver halide produces a precipitate of a different colour

Exam Tip

The acidification step in the halide ion test must be done with nitric acid rather than hydrochloric acid, as HCl contains chloride ions which would interfere with the results.

Author: Francesca

Fran has taught A level Chemistry in the UK for over 10 years. As head of science, she used her passion for education to drive improvement for staff and students, supporting them to achieve their full potential. Fran has also co-written science textbooks and worked as an examiner for UK exam boards.

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