CAPE Chemistry Unit 1 · 2005 · Paper 1

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)1 markDefine empirical formula.
2. 1(a)(ii)1 markDefine molecular formula.
3. 1(b)2 marksGive an example of a compound for which the molecular formula is different from the empirical formula, writing the respective formulae.
4. 1(c)6 marksUse the data provided to determine the molecular formula of X.
5. 2(a)2 marksReferring to Figure 1, explain why the chemical reaction occurring in batteries is described as a redox reaction.
6. 2(b)(i)2 marksWrite the balanced ionic equation for the reaction that occurs, given the half-equations: SO₂(g) + 2H₂O(l) → SO₄²⁻(aq) + 2e⁻ + 4H⁺(aq) Cr₂O₇²⁻(aq) + 6e⁻ + 14H⁺ → 2Cr³⁺(aq) + 7H₂O(l)
7. 2(b)(ii)2 marksState the change in oxidation number in any ONE identified reagent in the reaction.
8. 2(c)4 marksSelect THREE named elements and describe an experiment, including observations, to show how the elements selected can be listed in order of oxidizing or reducing ability.
9. 3(a)(i)1 markState the behaviour of gases described by Boyle's law.
10. 3(a)(ii)1 markState the behaviour of gases described by Charles' law.
11. 3(b)(i)2 marksState TWO assumptions made when the kinetic theory is used to explain the behaviour of gases.
12. 3(b)(ii)2 marksDescribe how the kinetic theory explains EITHER Boyle's law OR Charles' law.
13. 3(c)4 marksA mass of gas occupies 1.00 dm³ at a given pressure and 25 °C. Assuming ideal behaviour, calculate its volume at 30 °C, stating any assumptions made.
14. 4(a)2 marksIdentify ANY TWO functional groups that are present in lactic acid or alanine.
15. 4(b)(i)2 marksDistinguish between electrophiles and nucleophiles.
16. 4(b)(ii)2 marksDistinguish between homolytic and heterolytic bond fission.
17. 4(c)(i)2 marksWrite the chemical equation for this reaction.
18. 4(c)(ii)a)1 markOutline the bond-breaking step involved in the reaction of 2-chloro-2-methylpropane with sodium hydroxide.
19. 4(c)(ii)b)1 markOutline the bond-forming step involved in the reaction of 2-chloro-2-methylpropane with sodium hydroxide.
20. 5(a)(i)2 marksSuggest an explanation for the difference in behaviour of benzene under the stated conditions.
21. 5(a)(ii)2 marksWrite an equation to illustrate the reaction between sulphuric acid and nitric acid.
22. 5(b)(i)4 marksIllustrate the reaction mechanism for the nitration of benzene.
23. 5(b)(ii)1 markWhat is the name given to the mechanism outlined for the nitration of benzene?
24. 5(c)1 markNitrobenzene reacts with tin and concentrated hydrochloric acid. State the product formed.
25. 6(a)(i)1 markState the meaning of the term pKa.
26. 6(a)(ii)2 marksExplain the significance of the given pKa values.
27. 6(a)(iii)2 marksDescribe the features of EACH of the organic molecules that account for the difference in pKa values.
28. 6(b)(i)2 marksGive the displayed formula of L-threonine in an acidic solution.
29. 6(b)(ii)3 marksExplain why L-threonine has a high melting point and is soluble in water.
30. 7(a)4 marksBriefly explain how vaporization, ionization, separation, and detection of a sample are achieved in a mass spectrometer.
31. 7(b)(i)2 marksGive the m/z values of the molecular ion peak and the peak representing the most stable fragment in the spectrum.
32. 7(b)(ii)3 marksSuggest possible structures for the fragments with m/z values of 29, 57, and 59.
33. 7(b)(iii)1 markDeduce the structure of the product of the reaction described.
34. 8(a)(i)1 markDescribe the property of the nuclei that allows them to be detected in NMR analysis.
35. 8(a)(ii)1 markGive the symbols for the TWO main nuclei found in organic molecules that are detected by NMR analysis.
36. 8(a)(iii)2 marksState the changes that occur in the molecules of a sample when subjected first to an external magnetic field and then to radio wave signals.
37. 8(b)(i)3 marksWhich TWO functional groupings are indicated by the chemical shift values? Explain your reasoning.
38. 8(b)(ii)3 marksSuggest a structure for the organic compound C₉H₁₀O.
39. 9(a)(i)1 markSuggest a type of solvent that could be used to isolate an organic product from an aqueous reaction mixture.
40. 9(a)(ii)2 marksDescribe TWO properties the solvent should have for this extraction method to work.
41. 9(a)(iii)2 marksBriefly explain ONE principle on which solvent extraction is based.
42. 9(b)(i)1 markSuggest a method that would be suitable to extract natural organic compounds from plant material.
43. 9(b)(ii)2 marksGive TWO features of the extraction method suggested in (b)(i) that allow the stated objectives to be achieved.
44. 9(b)(iii)2 marksExplain why the features mentioned in (b)(ii) are essential.