A technician has three bottles of white solids. The labels have fallen off. The technician knows that the solids are sodium carbonate, sodium sulfate and sodium chloride, but does not know which is which.
A student suggests carrying out a flame test on each solid. Explain why this would not help to identify the solids.
Complete the word equation for the reaction of sodium carbonate with dilute hydrochloric acid.
sodium carbonate + hydrochloric acid → \rightarrow\,→ sodium chloride + ........ + ........
Another student adds dilute hydrochloric acid and then silver nitrate solution to one of the solids. A white precipitate forms. The student concludes that the solid is sodium chloride.
Explain why this conclusion is not valid.
Devise a plan to identify which bottle contains each solid. Your plan should include the tests, how you would carry them out, and the results you would expect for each solid.
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.