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2 marksUncertainty in Measurements

CAPE Chemistry Unit 2 · 2011 · Paper 2 · Question 2(c)(i)

Four students determined the percentage of acetic acid in vinegar, repeating the titration four times.

Complete Table 2 by calculating the standard deviation (SD) of EACH of the four sets of results using the provided formula.

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Other parts of this question

  1. 2(a)Distinguish between the terms 'precision' and 'accuracy'.[3 marks]
  2. 2(b)List THREE pieces of apparatus that could be used to accurately measure 50 cm³ of a liquid.[2 marks]
  3. 2(c)(ii)Evaluate the results obtained by EACH student by commenting on the accuracy and precision of EACH set of titre volumes.[4 marks]
  4. 2(d)Outline the experimental steps that should be taken by a student to calibrate a 10 cm³ pipette.[4 marks]

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