Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Chemical Tests
68 practice questions
Topics covered
Practice questions
61–68 of 68
Question 61
2 marks · Hard
Answer and see the solution →Describe the steps you would take to test a solution to determine whether it contains any halide ions (chloride, bromide, or iodide) using silver nitrate.
Question 62
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 63
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 64
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 65
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.
Question 66
6 marks · Normal
Answer and see the solution →A student is given two separate white solids, labelled X and Y. X is known to be either sodium carbonate or ammonium chloride. Y is a mixture of calcium carbonate and ammonium chloride.
(a)Describe a test to identify which solid, X or Y, contains the carbonate ion. Calculate the minimum volume of 1.0 mol/dm³ hydrochloric acid required to completely react with 0.05 mol of carbonate present in one of the solids. Show your working.
(i)[1 mark]State what you would observe when dilute hydrochloric acid is added to a carbonate.
(ii)[1 mark]Write the ionic equation for the reaction of a carbonate ion with an acid.
(iii)[1 mark]Calculate the minimum volume (in cm³) of 1.0 mol/dm³ hydrochloric acid required to react completely with 0.05 mol of carbonate ion. (Assume carbonate is CO₃²⁻.)
(b)Solid Y is warmed with sodium hydroxide solution. Ammonia gas is produced.
Describe the test and give a calculation to show how many moles of ammonium ions would be present if 672 cm³ of ammonia gas is collected at room temperature and pressure. (1 mol of gas occupies 24,000 cm³ at r.t.p.)
(i)[1 mark]Describe how to test for ammonia gas.
(ii)[1 mark]Calculate the number of moles of ammonia gas in 672 cm³ at r.t.p.
(iii)[1 mark]Write the ionic equation for the reaction of ammonium ions with hydroxide ions.
Question 67
6 marks · Normal
Answer and see the solution →A student needs to check if water and carbonate ions are present in two different solutions. The first solution is labelled A (clear, colourless liquid). The second is labelled B (pale green solution).
(a)[2 marks]Describe how the student could test solution A to check if it is pure water. Explain the result that would show if it is not pure.
(b)[2 marks]The student adds a white powder to solution B and observes effervescence. The gas produced is bubbled through limewater which turns cloudy.
Explain what ions are present in the white powder and write the ionic equation for the reaction.
(c)[2 marks]The student wishes to know if any ammonium ions are present in the white powder. Describe a test for ammonium ions and explain how the result confirms their presence.
Question 68
6 marks · Normal
Answer and see the solution →A student tests an unknown powder. To show if the powder contains water and carbonate ions, the following experiments are carried out.
(a)[2 marks]Describe the chemical test used to show if the powder contains water.
(b)A sample of the powder is added to dilute acid and gas is released. The gas is bubbled through limewater, which becomes cloudy.
(i)[1 mark]Identify the ion present responsible for the release of this gas.
(ii)[2 marks]Write the ionic equation for the reaction between this ion and dilute acid.
(iii)[1 mark]Suggest a physical test to confirm if the water in the sample is pure.