A technician finds four bottles of solid, A, B, C and D. The labels have fallen off.
The labels say:
iron(II) sulfate
lithium carbonate
potassium chloride
sodium bromide
The technician does some tests on each solid.
The table shows the results.
| Solid | Flame test | Add dilute hydrochloric acid to the solid | Add sodium hydroxide solution to a solution of the solid | Add dilute nitric acid, then silver nitrate solution, to a solution of the solid |
|---|---|---|---|---|
| A | red flame | fizzes; the gas turns limewater milky | no precipitate | fizzes; no precipitate |
| B | lilac flame | no change | no precipitate | white precipitate |
| C | yellow flame | no change | no precipitate | cream precipitate |
| D | no clear colour | no change | green precipitate | no precipitate |
Name the gas given off when solid A reacts with dilute hydrochloric acid.
Name the green precipitate formed by solid D.
Identify solids A, B, C and D.
Explain how the results identify the positive ion and the negative ion in each solid.
The results do not prove which negative ion is in solid D. Describe a further test, and its result, that would confirm the negative ion in solid D.
52 exam-style questions on OCR GCSE Chemistry 4.2 Identifying the products of chemical reactions, covering 4.2.1 Tests to identify gases, 4.2.2 Tests for aqueous ions and flame tests, and 4.2.3 Instrumental methods of analysis. Each one has a worked solution and a mark scheme showing where the marks go.