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3 marksEnergetics

CSEC Chemistry · May/June 2009 · Paper 2 · Question 1(a)(ii)b)

Figure 2 shows thermometer readings for the highest temperature recorded for each addition of zinc to CuSO₄. The initial temperature in each case is 28°C.

On the graph paper provided on page 5, plot the temperature change (ΔT) against mass of zinc added.

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Other parts of this question

  1. 1(a)(i)a)Describe what would be observed in the polystyrene cup in Figure 1.[2 marks]
  2. 1(a)(i)b)What does the observation you described in a) above indicate about the relative positions of zinc and copper in the reactivity series?[1 mark]
  3. 1(a)(i)c)Distinguish between an exothermic and an endothermic reaction.[2 marks]
  4. 1(a)(ii)a)Using the readings in Figure 2, complete Table 1 to show the final thermometer readings, and the changes in temperature.[2 marks]
  5. 1(a)(iii)c)From your graph, deduce the temperature change (ΔT) that will occur when 1.0 g of zinc is added to the copper(II) sulphate solution.[1 mark]
  6. 1(a)(iii)Calculate the minimum mass of zinc required to completely react with 100 cm³ of 0.20 mol dm⁻³ copper(II) sulphate. Relative atomic mass of Zn = 65.[2 marks]
  7. 1(a)(iv)Use the information in (iii) above to explain why the different masses of zinc used in Experiments 4 and 5 give approximately the same change in temperature.[1 mark]
  8. 1(a)(v)Another group of students performs a similar experiment but uses silver instead of zinc. No temperature change is observed. Account for this observation.[2 marks]
  9. 1(b)(i)Complete Table 2 to show all of the possible inferences and write ionic equations where indicated.[2 marks]
  10. 1(b)(ii)Suggest a possible identity of the solid, R:[1 mark]
  11. 1(c)(i)Outline the procedure for the experiment.[2 marks]
  12. 1(c)(ii)List the materials necessary.[1 mark]
  13. 1(c)(iii)What evidence will result from your procedure to distinguish between the two acids?[1 mark]

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