In practical terms, identifying chloride (Cl⁻), bromide (Br⁻), and iodide (I⁻) ions in solutions of sodium chloride (NaCl), sodium bromide (NaBr), and sodium iodide (NaI) can be accomplished through various chemical tests:
1. **Silver Nitrate Test**:
- Add silver nitrate (AgNO₃) solution to the sample.
- White precipitate indicates chloride ions (AgCl), which are soluble in dilute ammonia.
- Cream precipitate indicates bromide ions (AgBr), sparingly soluble in dilute ammonia.
- Yellow precipitate indicates iodide ions (AgI), soluble in concentrated ammonia.
2. **Chlorine Water Test**:
- Passing chlorine gas through the solution containing bromide ions produces a yellowish-brown solution due to the formation of bromine (Br₂).
- Passing chlorine gas through the solution containing iodide ions produces a purple solution due to the formation of iodine (I₂).
3. **Addition of Chlorine Water and Carbon Tetrachloride**:
- Adding chlorine water and carbon tetrachloride to the solution containing iodide ions results in the formation of a violet or purple color at the interface due to the liberation of iodine, which dissolves in carbon tetrachloride.
These are some common methods used in practical chemistry laboratories to identify chloride, bromide, and iodide ions in solutions.
