This question is about qualitative analysis and the identification of ions.
A student investigated a sample of calcium chloride solution and a sample of potassium sulfate solution.
The student carried out flame tests using the following method:
State the flame colour produced by the calcium chloride solution.
Potassium compounds produce a characteristic lilac flame. Explain why the student's method did not produce a distinct lilac flame colour when testing the potassium sulfate solution.
In a separate set of tests, the student added sodium hydroxide solution dropwise until in excess to:
State the observations for both tests.
To confirm the presence of halide ions in the calcium chloride solution, the student first acidified the sample with dilute nitric acid. Name the reagent that must be added next to show the presence of chloride ions.
To test for the presence of sulfate ions in the potassium sulfate solution, the student first acidified the sample with dilute hydrochloric acid. Name the reagent added to show the presence of sulfate ions, and state the observation that indicates a positive result.
29 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.