A student carried out a series of tests on a solid, Z, in order to identify the ions that could be present. Her results are as follows: - Test 1: A flame test on solid Z produced a crimson flame. - Test 2: Solid Z was dissolved in water, and the solution was divided into three portions, A, B, and C. For Portion A, adding dilute sodium hydroxide solution produced a brown precipitate. For Portion B, adding dilute hydrochloric acid followed by barium chloride solution produced a white precipitate. For Portion C, adding dilute nitric acid followed by silver nitrate solution resulted in no change.
Identify the ion responsible for: (i) the crimson colour in the flame test; (ii) the brown precipitate when sodium hydroxide solution was added; (iii) the white precipitate when barium chloride solution was added.
Describe how the student should carry out a flame test on solid Z.
(i) Why was dilute hydrochloric acid added to the solution of solid Z before using barium chloride solution? (ii) Why should dilute sulfuric acid not be used in place of dilute hydrochloric acid in this test?
Suggest one negative ion that cannot be identified by a precipitation reaction.
35 exam-style questions on Edexcel IGCSE Chemistry Chemical tests. Each one has a worked solution and a mark scheme showing where the marks go.