Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Chemical Tests
68 practice questions
Topics covered
Practice questions
21–30 of 31 · Normal
Question 21
3 marks · Normal
Answer and see the solution →Explain how you can distinguish between the precipitates formed when chloride, bromide or iodide ions react with silver nitrate. In your answer, refer to both the name and the colour of each precipitate.
Question 22
4 marks · Normal
Answer and see the solution →The table shows the results of silver nitrate tests on four unknown solutions after they were all acidified with dilute nitric acid.
Solution Observation with AgNO3 after acidifying P White precipitate Q Yellow precipitate R No precipitate S Cream precipitate For each solution, write the name and formula of the ion responsible for the observation. If there is no precipitate, state 'none'.
Question 23
1 mark · Normal
Answer and check →A solution is acidified with dilute nitric acid and then tested with silver nitrate. Which observation indicates the presence of bromide ions?
- A.A yellow precipitate forms.
- B.A white precipitate forms.
- C.A cream precipitate forms.
- D.No precipitate forms.
Question 24
2 marks · Normal
Answer and see the solution →State two reasons why nitric acid is used, and not hydrochloric acid, when testing for halide ions with silver nitrate.
Question 25
4 marks · Normal
Answer and see the solution →(a)[2 marks]Name the compounds formed when silver nitrate is added to solutions containing (i) chloride, (ii) bromide, and (iii) iodide ions.
(b)[2 marks]Give the colour of each compound formed in part (a).
Question 26
2 marks · Normal
Answer and see the solution →State the names and colours of the precipitates formed when silver nitrate is added to (a) a solution containing bromide ions and (b) a solution containing iodide ions, after acidification with nitric acid.
Question 27
4 marks · Normal
Answer and see the solution →(a)[3 marks]Describe the steps you would take to test a sample for iodide ions using silver nitrate. Include all reagents added and any important precautions.
(b)[1 mark]What result would indicate that iodide ions are present?
Question 28
3 marks · Normal
Answer and see the solution →A student tests three unknown solutions by first adding dilute nitric acid and then silver nitrate solution. The results are:
Observations for unknown solutions after addition of silver nitrate Solution Observation A white precipitate B cream precipitate C no visible change Question 29
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 30
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.