A student adds dilute hydrochloric acid to a solution of an unknown compound until no more bubbles form. The gas turns limewater milky. Barium chloride solution is then added to the same mixture and a white precipitate forms.
Which conclusion is correct?
Carbonate ions only; the white precipitate is barium carbonate
Sulfate ions only; the gas was made by sulfate ions reacting with acid
Carbonate and sulfate ions; the acid had already removed the carbonate
Carbonate and chloride ions; chloride ions formed the white precipitate
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.