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3 marksEnergetics

CAPE Chemistry Unit 1 · 2006 · Paper 2 · Question 8(a)(iii)

The enthalpy of solution of sodium chloride is determined in a school laboratory. The results of four trials are presented in Table 4 below. The theoretical value is + 5.00 KJ mol-1.

Calculate the standard deviation of the data and explain the significance of the value.

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Other parts of this question

  1. 8(a)(i)Calculate the mean of ΔHsoln NaCl from the data.[2 marks]
  2. 8(a)(ii)Comment on the precision and accuracy of the results.[3 marks]
  3. 8(b)(i)Discuss whether each instrument is appropriate for the measurement taken and suggest possible alternatives where necessary.[6 marks]
  4. 8(b)(ii)Give TWO reasons for calibrating an instrument such as a thermometer and suggest TWO steps involved.[4 marks]
  5. 8(c)Use the calibration curve in Figure 2 to determine the density of a block of metal that displaces a volume of 4.0 cm³.[2 marks]

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