CSEC Chemistry · May/June 2005 · Paper 2

43 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 marksIn the space below, construct a suitable table and record on it, the temperatures at which the reaction took place with the corresponding times in seconds for the formation of sulphur.
2. 1(a)(ii)3 marksUsing the graph paper provided on page 5, plot a graph of temperature versus time in seconds.
3. 1(a)(iii)1 markWhat conclusion can be drawn about the rate of the reaction from the graph?
4. 1(a)(iv)2 marksFrom the graph, determine the time expected to be taken for the appearance of the sulphur precipitate if the reaction were carried out at 50°C. Indicate on your graph how you arrived at your answer.
5. 1(a)(v)2 marksFrom the information given on page 3 in the introduction to this question, write a balanced chemical equation for the reaction between aqueous sodium thiosulphate and hydrochloric acid.
6. 1(b)(i)10 marksHeat a small portion of solid Y in a test tube, gently at first and then strongly. Observations: colourless gas evolved with a choking odour; turns acidified potassium dichromate solution from orange to green.…
7. 1(b)(ii)10 marksTo the remaining portion of solid Y, add 20 cm³ of distilled water, stir to dissolve and filter. Collect the filtrate and divide into three (3) equal portions. Observations: filtrate is pale green in colour. Inferences:
8. 1(b)(iii)10 marksTo the first portion of the filtrate from (b) above, add aqueous sodium hydroxide slowly until in excess. Observations: a green precipitate is formed; insoluble in excess aqueous sodium hydroxide. Inferences:
9. 1(b)(iv)10 marksTo the second portion of the filtrate from (b) above, add aqueous silver nitrate followed by aqueous ammonia. Observations: white precipitate is formed; insoluble in aqueous ammonia. Inferences (ionic equation required):
10. 1(b)(v)10 marksTo the third portion of the filtrate from (b) above, add aqueous barium nitrate followed by aqueous nitric acid. Observations: a white precipitate is formed; precipitate readily dissolves in aqueous nitric acid with the…
11. 1(c)(i)8 marksHypothesis to be tested
12. 1(c)(ii)8 marksMaterials and apparatus
13. 1(c)(iii)8 marksMethod
14. 1(c)(iv)8 marksVariables controlled
15. 1(c)(v)8 marksData to be collected
16. 1(c)(vi)8 marksResults linked to hypothesis
17. 2(a)3 marksDraw a labelled diagram to illustrate the number of protons, neutrons and electrons present in an atom of B.
18. 2(b)2 marksTo which group of the periodic table does element A belong? Give a reason for your answer. Element A belongs to Group _____. Reason: _____.
19. 2(c)3 marksWhat type of chemical bonding will be formed when A combines with B? Give a reason for your answer. Type of chemical bonding: _____. Reason: _____.
20. 2(d)(i)1 markWrite the chemical formula of the compounds expected to be formed when atoms of element A combine with those of element B. Chemical formula: _____.
21. 2(d)(ii)1 markWrite the chemical formula of the compounds expected to be formed when atoms of element A combine with each other. Chemical formula: _____.
22. 2(d)(iii)2 marksBased on your answer in (d)(i) on page 9 and the information given in the question, calculate the mass of compound that will be formed when 54g of B reacts completely with A.
23. 2(e)3 marksState THREE likely differences in the properties of the compound formed in (d)(i) when compared to the compound formed in (d)(ii). THREE differences in properties: _____.
24. 3(a)6 marksDraw FULLY DISPLAYED chemical structures for EACH of the following organic compounds identified in the reaction scheme above: C, E, F.
25. 3(b)2 marksDraw the partial structure of the polymer G to show THREE repeating units.
26. 3(c)(i)2 marksName the type of reaction involved in the conversion of A to E.
27. 3(c)(ii)2 marksName the type of reaction involved in the conversion of B to F.
28. 3(d)2 marksDescribe a chemical test to identify the functional group present in compound E. In your answer you should indicate the reagent to be used and write a chemical equation for the reaction which occurs. Reagent: _____.…
29. 3(e)(i)4 marksState the reagents and reaction conditions necessary to convert E to A. Reagent(s): _____. Reaction condition: _____.
30. 3(e)(ii)4 marksState the reagents and reaction conditions necessary to convert F to B. Reagent(s): _____. Reaction condition: _____.
31. 4(a)3 marksWhat changes occur during a reaction that can account for this fact?
32. 4(b)(i)1 markDefine the term 'heat of neutralization'.
33. 4(b)(ii)2 marksIt is observed that whenever a strong acid (such as HCl or HNO₃) is completely neutralized by a strong base (such as NaOH or KOH), the heat of neutralization (in kJ mol⁻¹) is the same. Account for this observation.
34. 4(c)(i)a)1 markThe number of moles of KNO₃ used in the experiment.
35. 4(c)(i)b)1 markThe heat change for the reaction.
36. 4(c)(i)c)2 marksThe enthalpy change in kJ mol⁻¹ for the reaction.
37. 4(c)(ii)1 markState ONE assumption you made in your calculation.
38. 4(c)(iii)3 marksDraw a labelled energy profile diagram to represent the enthalpy change for the reaction.
39. 5(a)2 marksWould Q be electrically conducting or not? Give a reason for your answer.
40. 5(b)3 marksState the expected reaction of Q with water. Include a chemical equation.
41. 5(c)2 marksFurther investigations reveal that on exposure to oxygen, the metal Q becomes chemically inert. State a possible reason for this.
42. 5(d)4 marksHow would the effect of heat on this metal nitrate of Q differ from that of sodium nitrate? Illustrate your answer by means of suitable chemical equations. Effect of heat on sodium nitrate: _____. Effect of heat on the…
43. 5(e)4 marksBriefly outline how a dry sample of the sulphate of Q can be prepared from a sample of the metal nitrate of Q. Include an ionic equation to illustrate your method of preparation.