A student adds sodium hydroxide solution, a few drops at a time, to four solutions. The student then adds excess sodium hydroxide solution to each one.
Table: The observations made when sodium hydroxide solution is added to four solutions
| Solution | Observation |
|---|---|
| 1 | blue precipitate |
| 2 | green precipitate |
| 3 | brown precipitate |
| 4 | white precipitate that dissolves when excess sodium hydroxide solution is added |
Name the metal ion in each solution. Use Table.
Give the colour of the precipitate formed when sodium hydroxide solution is added to a solution containing magnesium ions.
Explain why sodium hydroxide solution alone cannot be used to tell the difference between a solution of calcium ions and a solution of magnesium ions.
Describe a test that would tell the difference between a solution of calcium ions and a solution of magnesium ions. Give the results of the test.
40 exam-style questions on AQA GCSE Chemistry 8.3 Identification of ions by chemical and spectroscopic means, covering 8.3.1 Flame tests, 8.3.2 Metal hydroxides, 8.3.3 Carbonates, 8.3.4 Halides, 8.3.5 Sulfates, 8.3.6 Instrumental methods, and 8.3.7 Flame emission spectroscopy. Each one has a worked solution and a mark scheme showing where the marks go.