CAPE Chemistry Unit 1 · 2007 · Paper 2

40 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 marksUse Hess's law to calculate the enthalpy change for the following reaction: 2Mg (s) + O2(g) → 2MgO(s)
2. 1(b)(i)1 markExplain the reason for stirring the mixture at regular intervals.
3. 1(b)(ii)2 marksGiven that the initial and final temperatures are 28°C and 57°C respectively, sketch a typical graph for the results of the experiment to illustrate how the student arrived at the temperature change, ΔT, for the…
4. 1(b)(iii)1 markGive the main source of error for the experiment.
5. 1(b)(iv)3 marksCalculate the enthalpy change, in kJ mol⁻¹ of Mg for the reaction at constant pressure, given ΔT = 29.0°C, C = 4.20 Jg⁻¹ °C⁻¹. The density of dilute HCl is 1.0g cm⁻³.
6. 1(c)(i)1 markUse the results of your calculation in (b)(iv) above to state whether the reaction is endothermic or exothermic.
7. 1(c)(ii)4 marksDraw a clearly labelled energy profile diagram for the reaction between magnesium and hydrochloric acid. Include on your diagram the enthalpy change for the reaction.
8. 2(a)(i)1 markExplain what is meant by the term 'weak acid'.
9. 2(a)(ii)1 markWrite an expression for the dissociation constant, Kₐ, of methanoic acid.
10. 2(b)(i)2 marksUsing Bronsted-Lowry theory, explain what is meant by a strong base.
11. 2(b)(ii)2 marksCalculate the pH of the standard NaOH solution.
12. 2(b)(iii)2 marksThe concentration of methanoic acid in Solution Y is found to be 6.0 x 10⁻³ mol dm⁻³. Calculate the pH of Solution Y.
13. 2(b)(iv)1 markSuggest a suitable indicator for the titration between methanoic acid and sodium hydroxide.
14. 2(b)(v)4 marksSketch a graph to illustrate the changes in pH that take place during the titration.
15. 2(c)2 marksAnt stings can be treated with baking soda, NaHCO₃. Suggest, with the aid of an equation, how baking soda helps to relieve the effect of the sting.
16. 3(a)(i)4 marksDescribe the reaction of barium metal with water. Include a balanced equation.
17. 3(a)(ii)2 marksExplain why the use of barium sulphate is acceptable in the X-ray analysis even though Ba²⁺ ions are toxic.
18. 3(b)(i)2 marksPredict EACH of the following: Thermal stability of RaCO₃ relative to the other Group II carbonates
19. 3(b)(ii)2 marksPredict EACH of the following: Ease of reaction between radium and oxygen
20. 3(c)2 marksMagnesium oxide is used in the walls of industrial furnaces. Suggest an explanation for this usage.
21. 3(d)(i)1 markIdentify the gas evolved on heating Compound A.
22. 3(d)(ii)2 marksIdentify the TWO gases evolved on heating Compound B.
23. 3(d)(iii)2 marksDeduce the molecular formulae of the two calcium salts. Compound A: Compound B:
24. 4(a)(i)2 marksState TWO properties of an ideal gas.
25. 4(a)(ii)5 marksUse the ideal gas equation to calculate the number of moles of gas produced in an air bag of volume 40.0 dm³ at a pressure of 2.0 x 10² KPa and a temperature of 30°C.
26. 4(a)(iii)2 marksGiven that the mass of gas produced in the air bag is 90.0 g, use the answer from (a)(ii) to calculate the molar mass of the gas and suggest its identity.
27. 4(a)(iv)2 marksWrite the equation for the decomposition of NaN₃.
28. 4(b)(i)2 marksState the conditions of temperature and pressure under which gases deviate from ideality.
29. 4(b)(ii)2 marksDescribe the property of the gas molecules that is responsible for the deviation from ideality.
30. 5(a)(i)2 marksState and explain the effect of EACH of the following on the rate of a chemical reaction: A catalyst
31. 5(a)(ii)3 marksState and explain the effect of EACH of the following on the rate of a chemical reaction: Concentration of the reactants
32. 5(b)(i)2 marksUse the data given in Table 1 to calculate the order of the reaction with respect to the SO₂Cl₂.
33. 5(b)(ii)4 marksWrite the rate equation for the reaction and calculate the value and units for the rate constant.
34. 5(b)(iii)2 marksCalculate t₁/₂ for the reaction.
35. 5(b)(iv)2 marksState and explain the effect on the rate of dissociation of SO₂Cl₂, of carrying out the experiment at a higher temperature.
36. 6(a)(i)4 marksDefine the term 'ligand' and identify two ligands in the haemoglobin structures in Figure 1.
37. 6(a)(ii)2 marksState and explain the principle on which the reaction in Figure 1 is based.
38. 6(b)(i)3 marksUsing the information in Figure 1, account for the toxic effect of carbon monoxide at high concentrations.
39. 6(b)(ii)2 marksSuggest a treatment for a patient suffering from overexposure to carbon monoxide and give a reason for your suggestion.
40. 6(c)4 marksAccount for the origin of colour in transition metal complexes.