The label on a bottle of mineral water lists the ions dissolved in the water. A food scientist checks the label by testing the water for sulfate ions and chloride ions.
Describe how the scientist tests the water for sulfate ions and give the positive result.
Write the ionic equation, with state symbols, for the reaction that takes place in a positive test for sulfate ions.
Mineral water also contains hydrogencarbonate and carbonate ions. Explain why the water is acidified with dilute hydrochloric acid before the sulfate test.
To test for chloride ions, the scientist acidifies a fresh sample with dilute nitric acid and then adds silver nitrate solution.
Explain why dilute hydrochloric acid must not be used to acidify the sample in this test.
Write the ionic equation, with state symbols, for the formation of the precipitate in a positive test for chloride ions.
35 exam-style questions on Edexcel GCSE Chemistry 10.1 Qualitative analysis: tests for ions, covering 10.1.1 Principles of ion tests and flame tests, 10.1.2 Tests for cations and for ammonia, 10.1.3 Tests for anions, 10.1.4 Identification of ions in unknown salts, and 10.1.5 Instrumental methods of analysis. Each one has a worked solution and a mark scheme showing where the marks go.