CSEC Chemistry · January 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)3 marksUsing the thermometer readings in Figure 1, complete Table 1 by recording the temperatures for additions of 5 cm³, 15 cm³ and 25 cm³ of H₂SO₄.
2. 1(b)(i)4 marksPlot the graph of temperature against volume of acid added using the axes provided in Figure 2.
3. 1(b)(ii)2 marksDraw two lines of best fit through the points on the graph: one where temperature is increasing and one where temperature is decreasing.
4. 1(b)(iii)2 marksShow the end point of the reaction on the graph and record the corresponding volume.
5. 1(c)2 marksDistinguish between a 'strong acid' and a 'weak acid'.
6. 1(d)2 marksWrite a balanced chemical equation for the reaction between NaOH and H₂SO₄.
7. 1(e)2 marksCalculate the number of moles of H₂SO₄ used in the reaction.
8. 1(f)2 marksCalculate the number of moles of NaOH in 25 cm³ of the solution.
9. 1(g)2 marksCalculate the concentration of NaOH, in mol dm⁻³.
10. 1(h)1 markCalculate the concentration of NaOH in g dm⁻³, given the molar mass of NaOH = 40 g mol⁻¹.
11. 1(i)2 marksState whether the reaction in the styrofoam cup was exothermic or endothermic and explain your answer.
12. 1(j)1 markState ONE safety precaution that should have been taken during the experiment.
13. 2(a)(i)1 markDefine the term 'allotrope'.
14. 2(a)(ii)2 marksIdentify the names of R and S.
15. 2(a)(iii)1 markState whether R is an ionic, simple covalent or giant covalent structure.
16. 2(a)(iv)3 marksSketch the structure of R using solid lines (—) for strong bonds and dotted lines (••••••) for weak bonds.
17. 2(a)(v)2 marksExplain why R conducts electricity but S does not conduct electricity.
18. 2(b)(i)1 markDeduce the type of bonding present in Solid T.
19. 2(b)(ii)1 markState the appearance that Solid T is expected to have.
20. 2(c)(i)2 marksCompare the arrangement of particles in solids with the arrangement of particles in liquids.
21. 2(c)(ii)2 marksState the process that occurs when solid iodine is heated to form a purple gas, and give ONE other example of a compound that undergoes the same process.
22. 3(a)(i)2 marksDefine the term 'structural isomerism'.
23. 3(a)(ii)2 marksDraw the fully displayed structure of 2-methylbutane.
24. 3(a)(iii)3 marksDraw and name ONE other structural isomer of C₅H₁₂.
25. 3(b)(i)1 markWhat is the functional group of ethanol, CH₃CH₂OH?
26. 3(b)(ii)5 marksComplete Table 2 by inserting the reaction conditions and drawing the fully displayed structures of the products formed for the two reactions of ethanol.
27. 4(a)(i)4 marksComplete Table 3 showing the three subatomic particles and their relative masses and charges.
28. 4(a)(ii)5 marksConsider the notation of an atom of an unknown element, ²⁹₁₄A. Draw a labelled diagram to illustrate the location, arrangement and number of EACH type of subatomic particle in Element ²⁹₁₄A.
29. 4(b)2 marksCalculate the number of atoms in 80.0 g of calcium. [Relative atomic mass of Ca = 40; Avogadro's constant = 6.0 × 10²³]
30. 4(c)(i)3 marksExplain the chemical process that can account for these observations.
31. 4(c)(ii)1 markState ONE other example that demonstrates this process.
32. 5(a)4 marksIdentify the types of reactions numbered 1, 2, 3 and 4 in Figure 3.
33. 5(b)(i)2 marksIdentify suitable reagents and reaction conditions used for converting Compound A to Compound B via Reaction 1.
34. 5(b)(ii)2 marksIdentify suitable reagents and reaction conditions used for converting Compound A to Compound C via Reaction 2.
35. 5(c)(i)1 markGiven that R is an ethyl group, state the molecular formula for Compound A.
36. 5(c)(ii)2 marksHence, write a balanced chemical equation for Reaction 3.
37. 5(d)4 marksDescribe a chemical test that can be used to distinguish Compound A from Compound B.
38. 6(a)(i)2 marksDescribe a test that could be used to identify the gaseous product formed.
39. 6(a)(ii)1 markA sample of the gas was collected by downward delivery. State the physical property of the gas which supports this method of collection.
40. 6(a)(iii)2 marksWrite a chemical equation, including state symbols, for the reaction between hydrochloric acid and sodium hydrogen carbonate.
41. 6(b)2 marksWrite an ionic equation for the reaction of magnesium with dilute hydrochloric acid.
42. 6(c)(i)3 marksSome farmers use ammonium sulfate fertilizers in the presence of a base. Explain why this is NOT a good practice.
43. 6(c)(ii)3 marksList TWO uses of silicon and ONE use of phosphorus.
44. 6(c)(iii)2 marksSulfur burns in air to produce a gas that dissolves in water to give a colourless solution. Identify the gas formed and state the effect that the solution would have on blue litmus paper.