Monitoring and Management > 3. Manufactured Products >
Deduce the ions present in a sample from the results of tests
Perform first-hand investigations to carry out a range of tests, including flame tests, to identify the following ions:
- phosphate
- sulfate
- carbonate
- chloride
- barium
- calcium
- lead
- copper
- iron
| Cation | Precipitate test(s) | Flame test(s) | Other Test(s) |
| Barium (Ba2+) | • SO42-: White • OH– or F+: None | Yellow–green | – |
| Calcium (Ca2+) | • SO42-: White • F–: White | Orange–red | – |
| Lead (Pb2+) | • Cl–: White • I–: Yellow | – | – |
| Copper (Cu2+) | OH–: Blue, dissolves in NH3 to form deep blue solution | Blue–green | – |
| Iron II (Fe2+) | OH–: White, turns brown | – | Decolourises dilute potassium permanganate solution |
| Iron III (Fe3+) | OH–: Brown | – | SCN–: Deep red solution |
Cation tests
| Cation | Precipitate test(s) | Other test(s) |
| Carbonate (CO32-) | – | • pH between 8 and 11. • Acid (H+): Bubbles of colourless odourless gas (CO2) |
| Sulfate (SO42-) | • Ba(NO3)2 (to acidified sample): Thick white • Pb(NO3)2 (to acidified sample): White | – |
| Chloride (Cl–) | AgNO3 (to acidified sample): Thick white, dissolves in ammonia and darkens in sunlight | – |
| Phosphate (PO43-) | • NH4 followed by Ba(NO3)2: White • Mg2+ in an ammonia, ammonium nitrate buffer: White | – |
Anion tests
Copper flame test