12 5 Tests are carried out on aqueous solutions of two salts, X and Y. (a) X contains one cation and one anion. The observations for each test are recorded in the table. (i) Complete the table by writing the names or formulae of the species. (2) Test Observation Inference Test 1 Add aqueous sodium hydroxide to an aqueous solution of X A green precipitate forms The precipitate turns brown on the top after a few minutes The cation in X is ..................................................................................................... Test 2 To an aqueous solution of X, add dilute hydrochloric acid followed by aqueous barium chloride A white precipitate forms The anion in X is ..................................................................................................... (ii) Write the ionic equation for the reaction between the cation in X and aqueous sodium hydroxide in Test 1. Include state symbols. (2) (iii) Give a reason why the green precipitate turns brown on the top after a few minutes. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (iv) Give a reason why dilute hydrochloric acid is needed in Test 2. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... Turn over 13 (b) Y contains one cation and one anion. The observations for each test are recorded in the table. (i) Complete the table by writing the names or formulae of the species. (2) Test Observation Inference Test 3 Add dilute aqueous ammonia to an aqueous solution of Y until it is present in excess A pale blue precipitate forms The precipitate dissolves in excess ammonia to form a deep blue solution The cation in Y is .......................................................................... Test 4 To an aqueous solution of Y, add dilute nitric acid followed by aqueous silver nitrate A white precipitate forms The anion in Y is .......................................................................... (ii) Give the formula of the complex ion present in the deep blue solution at the end of Test 3. (1) .................................................................................................................................................................................................................................................................................... (iii) Give a reagent that could be added to the mixture at the end of Test 4 to confirm the identity of the anion in Y. Include the observation when this reagent is added. (2) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 5 = 11 marks)