Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Chemical Tests
68 practice questions
Topics covered
Practice questions
21–28 of 28 · Easy
Question 21
3 marks · Easy
Answer and see the solution →The table shows the precipitates formed when different halide ions react with silver nitrate. Ion in solution Observation after adding silver nitrate Cl^- White precipitate Br^- Cream precipitate I^- Yellow precipitate Use the information in the table to answer the following questions.
(a)[1 mark]State the name and colour of the precipitate formed when a solution containing bromide ions is tested with silver nitrate.
(b)[1 mark]Identify which ion produces a yellow precipitate with silver nitrate.
(c)[1 mark]A student obtains a white precipitate when testing their solution with silver nitrate. Which halide ion is present?
Question 22
3 marks · Easy
Answer and see the solution →(a)[1 mark]State the observation when a solution containing iodide ions is tested with silver nitrate.
(b)[1 mark]State the observation when a solution containing chloride ions is tested with silver nitrate.
(c)[1 mark]State the observation when a solution containing bromide ions is tested with silver nitrate.
Question 23
1 mark · Easy
Answer and see the solution →State the reagent that must be added to a solution before silver nitrate to test for chloride, bromide, or iodide ions.
Question 24
2 marks · Easy
Answer and see the solution →A student adds silver nitrate to a solution to test for chloride ions. Before adding the silver nitrate, they add hydrochloric acid by mistake instead of another reagent. Explain, using your knowledge of chemical tests, why this mistake could affect the test result.
Question 25
5 marks · Easy
Answer and see the solution →This question is about testing for gases and for halide ions.
(a)[2 marks]Describe the chemical test for ammonia gas and state the positive result.
(b)A student wants to identify whether a colourless solution contains chloride ions.
i. State how the student would carry out a test for chloride ions.
ii. Name the precipitate formed and give its colour if chloride ions are present.
(i)[2 marks](ii)[1 mark]Question 26
5 marks · Easy
Answer and see the solution →This question is about observations when testing for ammonia gas and chloride ions.
(a)[1 mark]State what you would observe when ammonia gas is tested with damp universal indicator paper.
(b)A student adds dilute nitric acid and then silver nitrate solution to a solution of sodium chloride.
i. State the appearance of the precipitate formed.
ii. Give the name of the precipitate.
(i)[1 mark](ii)[1 mark](c)[2 marks]Explain why nitric acid is added before silver nitrate when testing for chloride ions.
Question 27
5 marks · Easy
Answer and see the solution →A student tests a colorless liquid. She wants to find out whether it is pure water or contains dissolved chloride ions from an unknown salt. She also has some ammonia solution for use in any tests required.
(a)[1 mark]Describe how the student could use a chemical test to show whether the liquid contains water, and explain what her result would mean about the presence of water.
(b)[2 marks]The student measures the boiling point of the liquid and finds it to be 102°C (at 1 atmosphere pressure). Calculate the difference between this boiling point and the boiling point of pure water under these conditions, and explain what this result shows about the purity of the liquid.
(c)[2 marks]To test for dissolved chloride ions, the student adds dilute nitric acid, followed by silver nitrate solution. She obtains a white precipitate. Explain why it is important to add the nitric acid before the silver nitrate solution in this test.
Question 28
5 marks · Easy
Answer and see the solution →Two unknown solutions, labelled X and Y, are tested. Solution X gives off a gas when warmed with sodium hydroxide. Solution Y forms a precipitate when tested with silver nitrate and dilute nitric acid.
(a)[2 marks]State the name of the gas given off by X when warmed with sodium hydroxide, and describe how you would test for it (including the result expected).
(b)[2 marks]Solution Y gives a yellow precipitate when tested with silver nitrate and dilute nitric acid. State which ion is present in Y, and the name and colour of the precipitate formed.
(c)[1 mark]Describe how you could distinguish between the precipitates formed with chloride and iodide ions using this test.