CAPE Chemistry Unit 2 · May/June 2021 · Paper 2

44 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)2 marksDefine the term 'structural isomerism'.
2. 1(a)(ii)4 marksIdentify TWO types of structural isomers, giving an example of EACH.
3. 1(b)(i)3 marksCalculate the molecular formula of the hydrocarbon, P.
4. 1(b)(ii)1 markWrite the displayed structural formula of P.
5. 1(b)(iii)4 marksOutline the reaction mechanism for the reaction of P with liquid bromine, using appropriate notations and equations.
6. 1(b)(iv)1 markIdentify the type of reaction mechanism outlined in (b)(iii) on page 5.
7. 1(c)(i)2 marksWrite the displayed structural formula of TWO isomers of Q.
8. 1(c)(ii)1 markState whether Compound Q exhibits geometric (cis/trans) isomerism.
9. 1(c)(iii)2 marksState TWO reasons for your answer in (c)(ii).
10. 1(c)(iv)4 marksOutline the mechanism for the reaction between Compound Q and HBr, using curved arrows to show the movement of electrons.
11. 1(c)(v)1 markState the type of reaction mechanism outlined in (c)(iv).
12. 1(d)(i)2 marksDescribe the observations expected for EACH of the following reactions: Aqueous bromine is added to liquid pentane (in sunlight).
13. 1(d)(ii)1 markDescribe the observations expected for EACH of the following reactions: Aqueous bromine is added to liquid pentane (without sunlight).
14. 1(d)(iii)2 marksDescribe the observations expected for EACH of the following reactions: Cold acidified potassium permanganate solution is added to liquid pentane.
15. 2(a)(i)4 marksDefine EACH of the following terms: Accuracy
16. 2(a)(ii)4 marksDefine EACH of the following terms: Precision
17. 2(b)(i)3 marksList THREE reasons why NaHCO₃ can be used as a primary standard.
18. 2(b)(ii)1 markState ONE reason why NaOH may NOT be used as a primary standard.
19. 2(c)(i)2 marksWrite the balanced equation for the reaction between sodium hydrogen carbonate and sulfuric acid.
20. 2(c)(ii)4 marksCalculate the mass (in grams) of the sodium hydrogen carbonate that the student would use to neutralize the acid, if 23.50 cm³ of the acid were used from the burette.
21. 2(d)(i)1 markDefine the term 'mean volume'.
22. 2(d)(ii)2 marksDetermine the mean volume from the titre values (to be used in the calculations).
23. 2(d)(iii)1 markDefine the term 'standard deviation'.
24. 2(d)(iv)3 marksUsing the following equation, justify the choice of the titre values selected in (d)(ii). S = √[Σ(x-x)² / (n-1)]
25. 2(e)4 marksWhen 0.612 g of hydrated barium chloride is heated to constant mass, 0.522 g of residue is formed. Deduce the formula of hydrated barium chloride.
26. 2(f)5 marksOutline FIVE experimental steps that should be carried out to determine the ethanoic acid content of the vinegar.
27. 3(a)(i)1 markState ONE reason why a catalyst is needed in this reaction.
28. 3(a)(ii)2 marksUsing Le Chatelier's principle, explain the effect of temperature on the direction of equilibrium for the ammonia formation.
29. 3(a)(iii)1 markState whether the temperatures used in the Haber-Bosch synthesis favour the formation of high yields of ammonia.
30. 3(a)(iv)2 marksComment on the statement “High pressure conditions favour the formation of ammonia in high yields."
31. 3(a)(v)2 marksWith reference to Figure 1 on page 13, state TWO possible design limitations that could lead to reduced product yield.
32. 3(a)(vi)1 markWrite the Kₚ expression for the Haber–Bosch process.
33. 3(a)(vii)1 markState the impact of the catalyst on the Kₚ of the reaction.
34. 3(b)(i)1 markComplete statement (i).
35. 3(b)(ii)1 markComplete statement (ii).
36. 3(b)(iii)2 marksComplete statement (iii).
37. 3(b)(iv)2 marksComplete statement (iv).
38. 3(b)(v)2 marksComment on the statement "The production of ammonia under standard atmospheric conditions would prove to be more efficient in the presence of a catalyst than the Haber-Bosch process."
39. 3(b)(vi)1 markIdentify another feature in the design that makes it 'green', apart from the use of a catalyst in the existing Haber-Bosch process.
40. 3(c)(i)2 marksWrite ONE equation that represents a step in this process.
41. 3(c)(ii)1 markWrite TWO statements that support the idea that ethanol is a green resource.
42. 3(c)(iii)2 marksState TWO factors that would preclude countries in the Caribbean from considering sugar beets as a viable source crop for ethanol production.
43. 3(c)(iv)2 marksDescribe the role of ethanol in this process.
44. 3(c)(v)3 marksMatch EACH formulation using the letters A, B or C with the appropriate set of characteristics that best describes it.