A scientist analyses a sample of river water using flame emission spectroscopy. Table shows the wavelengths of the main lines in the spectra of four metal ions, and the wavelengths of the lines produced by the sample.
Table: The wavelengths of the main lines in the flame emission spectra of four metal ions and of a sample of river water
| Metal ion | Wavelengths of main lines in nm |
|---|---|
| Lithium | 610 and 671 |
| Sodium | 589 and 819 |
| Potassium | 404 and 766 |
| Calcium | 423 and 622 |
| Sample of river water | 423, 589, 622 and 819 |
Name the two metal ions in the sample of river water. Use Table.
Explain why flame emission spectroscopy is more useful than a flame test for this sample.
Give one other piece of information that flame emission spectroscopy gives about the metal ions in the sample.
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.