| Anion | Reagent | Observation | Confirmation |
|---|---|---|---|
| CO₃²⁻ | Dilute HCl | Effervescence (fizzing) | Gas turns limewater milky |
| SO₄²⁻ | Dilute HCl + BaCl₂ | White precipitate | Insoluble in excess HCl |
| Cl⁻ | Dilute HNO₃ + AgNO₃ | White precipitate | Soluble in NH₃(aq) |
| Br⁻ | Dilute HNO₃ + AgNO₃ | Cream precipitate | Slightly soluble in NH₃ |
| I⁻ | Dilute HNO₃ + AgNO₃ | Yellow precipitate | Insoluble in NH₃(aq) |
• Dilute hydrochloric and nitric acids are irritants/corrosive — add carefully, wear goggles.
• Barium chloride is toxic if swallowed — wash hands and collect barium waste separately.
• Silver nitrate stains skin/clothes black and is toxic — collect all silver-halide precipitates as silver waste; do not pour down the sink.
• Ammonia solution is pungent and irritating — smell cautiously and use in a ventilated area.
• The gas from the carbonate test is CO₂ — direct the delivery tube into the limewater, not toward your face.
Each sample contains one unknown anion. Run the tests and deduce which.
Run the tests on this sample first, then identify the anion using your observations and the reference table.