Halides
Chemistry: AQA GCSE Higher, topic 8.3.6
Testing for Halides
Halide ions are negatively charged (they are anions). There are 2 steps to halide testing:
Add dilute nitric acid
- Add dilute nitric acid to an unknown solution.
- This removes carbonate ions. These could disrupt test results by forming a precipitate with the silver ions added in step 2.
Add silver nitrate
- Add silver nitrate to the same solution.
- If halide ions are present, they will form a precipitate with the silver ions:
- Ag+(aq) + Cl-(aq) → AgCl(s) (silver chloride is white).
- Ag+(aq) + Br-(aq) → AgBr(s) (silver bromide is cream).
- Ag+(aq) + I-(aq) → AgI(s) (silver iodide is pale yellow).
Test yourself on Halides
What colour are the following halide precipitates?
Which of the following are involved in testing for halides?
What are the chemical formulas of the three silver halide precipitates?
Why is dilute nitric acid added to a solution before it is tested with silver nitrate for halide ions?
Halide Testing