CSEC Chemistry · January 2005 · Paper 2

47 questions and parts from this paper. Open one to see it in full, then practise it on Quelpr and get it marked against the mark scheme.

1. 1(a)(i)4 marksFrom the results shown in Figure 1 construct a table to show experiment number, volume of acid added from the burette, volume of water added to the acid, and time taken for the magnesium to disappear.
2. 1(a)(ii)4 marksUsing the graph paper on page 4, plot a graph of time taken for the magnesium ribbon to disappear against volume of acid added from the burette.
3. 1(a)(iii)1 markExplain the shape of the graph.
4. 1(a)(iv)1 markUsing the data from the graph determine the time it would take for 25 cm³ of the acid to react with the magnesium ribbon.
5. 1(a)(v)2 marksWrite a balanced equation for the reaction of magnesium with hydrochloric acid.
6. 1(a)(vi)a)1 markCalculate the number of moles of Mg in 0.12 g (Relative Atomic Mass of Mg = 24).
7. 1(a)(vi)b)2 marksThe volume of hydrogen gas produced at r.t.p. when all the magnesium ribbon reacts with the acid (1 mole of gas at r.t.p. occupies 24 dm³).
8. 1(a)(vii)1 markExplain why it is necessary, for each experiment, to make up the volume of acid to 50 cm³ by adding water.
9. 1(b)(i)7 marksHeat a small sample of solid Z gently in a dry test tube. Observation: Pungent gas evolves which turns damp red litmus blue. Inference: (equation required).
10. 1(b)(ii)7 marksAdd approximately 2 cm³ of aqueous sodium hydroxide to a sample of solid Z and warm. Observation: A gas evolves which forms dense white fumes with hydrogen chloride. Inference: (equation required).
11. 1(b)(iii)7 marksDissolve a spatula full of solid Z in approximately 10 cm³ of deionized water. Divide the resulting mixture into 3 portions for tests iv - vi. Observation: A pale green solution is formed. Inference: (equation required).
12. 1(b)(iv)7 marksTo one portion of solution Z from (iii) above, add aqueous sodium hydroxide dropwise until in excess. Observation: A green gelatinous precipitate forms. The precipitate is insoluble in excess sodium hydroxide.…
13. 1(b)(v)7 marksTo another portion of solution Z from (iii) above, add dilute nitric acid followed by aqueous silver nitrate solution. Observation: No visible reaction seen. Inference: (ionic equation required).
14. 1(b)(vi)7 marksTo another portion of solution Z from (iii) above, add barium nitrate followed by dilute nitric acid. Observation: A white precipitate insoluble in dilute acid is produced. Inference: (ionic equation required).
15. 1(c)(i)1 markWrite up the Aim.
16. 1(c)(ii)2 marksWrite up the Method or procedure.
17. 1(c)(iii)1 markWrite up the Discussion of results: Data to be collected.
18. 1(c)(iii) continued2 marksWrite up the Discussion of results: Steps for doing calculations.
19. 1(c)(iii) continued1 markWrite up the Discussion of results as it relates to aim.
20. 2(a)3 marksCalculate the number of moles of Al(OH)₃ in 250 g of Suspension P. (Relative Atomic Mass: Al = 27, O = 16, H = 1).
21. 2(b)(i)2 marksExplain why the reaction stops after a while.
22. 2(b)(ii)4 marksOutline a suitable laboratory method for preparing a dry sample of calcium sulphate. Include a relevant equation in your answer.
23. 2(c)(i)1 markWhich of the Suspensions, P or Q, could serve as an antacid?
24. 2(c)(ii)2 marksWrite a chemical equation to support your answer to (c) (i).
25. 2(d)3 marksState THREE ways in which a colloid differs from a suspension.
26. 3(a)(i)3 marksCalculate the empirical formula of B (Relative Atomic Mass: C = 12; O = 16; H = 1).
27. 3(a)(ii)2 marksThe empirical formula for A is CH₂O. Deduce whether or not A and B belong to the same homologous series. Explain your answer.
28. 3(b)(i)2 marksCalculate the molecular formula for A and B. (The relative formula mass of both A and B = 60).
29. 3(b)(ii)4 marksCompounds A and B both react with sodium. Write the fully displayed structural formulae for A and B.
30. 3(c)(i)2 marksDescribe ONE chemical test that can be used to distinguish between A and B.
31. 3(c)(ii)2 marksWill both A and B be soluble in water? Give a reason for your answer.
32. 4(a)(i)1 markWhat will happen to the bulb when the electrolyte is replaced with pure water?
33. 4(a)(ii)1 markExplain your answer to (a) (i).
34. 4(b)(i)2 marksIdentify the gases in tubes A and B.
35. 4(b)(ii)5 marksBy considering the reactions that occur at the electrode surfaces, explain the occurrence of the 2:1 ratio in the gases collected in A and B. Use balanced ionic equations to support your answer.
36. 4(c)(i)1 markIf the bulb in Figure 3 is replaced with an ammeter, what will happen to the reading on the ammeter if the electrolyte is changed from dilute sulphuric acid to dilute methanoic acid?
37. 4(c)(ii)2 marksExplain your answer to (c) (i).
38. 4(d)3 marksWhat adjustments have to be made to Figure 3 in order to copper-plate a spoon?
39. 5(a)(i)2 marksWrite balanced equations for the reactions between hydrochloric acid and sodium sulphite.
40. 5(a)(ii)2 marksWrite balanced equations for the reactions between hydrochloric acid and sodium carbonate.
41. 5(a)(iii)1 markState ONE effect that the products from these two reactions could have on the environment.
42. 5(b)(i)4 marksDescribe the observations expected from tests (i) – (iv) in Table 2. Observations from: (i) Acidified potassium manganate (VII) with gas from sodium sulphite.
43. 5(b)(ii)4 marksDescribe the observations expected from tests (i) – (iv) in Table 2. Observations from: (ii) Aqueous calcium hydroxide with gas from sodium carbonate.
44. 5(b)(iii)4 marksDescribe the observations expected from tests (i) – (iv) in Table 2. Observations from: (iii) Damp blue litmus with gas from sodium sulphite.
45. 5(b)(iv)4 marksDescribe the observations expected from tests (i) – (iv) in Table 2. Observations from: (iv) Damp blue litmus with gas from sodium carbonate.
46. 5(c)3 marksWith reference to the gas produced when hydrochloric acid reacts with sodium sulphite, account for the observed changes in the acidified potassium manganate (VII) described in (b) (i) on page 14.
47. 5(d)3 marksDraw a diagram of the apparatus to show how the products formed from observation (b) (ii) could be separated.