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4 marksUncertainty in Measurements

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

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

Evaluate the results obtained by EACH student by commenting on the accuracy and precision of EACH set of titre volumes.

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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)(i)Complete Table 2 by calculating the standard deviation (SD) of EACH of the four sets of results using the provided formula.[2 marks]
  4. 2(d)Outline the experimental steps that should be taken by a student to calibrate a 10 cm³ pipette.[4 marks]

More practice: the rest of this paper · more Uncertainty in Measurements questions · all CAPE Chemistry Unit 2 past papers