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3 marksAcid/Base Equilibria

CAPE Chemistry Unit 1 · May/June 2022 · Paper 2 · Question 2(a)(iv)

Module 2: Kinetics and Equilibria. Acid-base behavior of extracted liquid from ants (pH 4.2).

Using Table 3 showing pH ranges of indicators, suggest with reasons which indicator is the most suitable for use in the titration in (iii).

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Other parts of this question

  1. 2(a)(i)Define the term 'pH'.[1 mark]
  2. 2(a)(ii)Calculate the hydrogen ion concentration of the colourless liquid with pH 4.2.[2 marks]
  3. 2(a)(iii)Twenty cm^3 of a solution with the same pH as the extracted liquid is titrated with 1 x 10^-4 mol dm^-3 aqueous sodium hydroxide. Sketch the titration curve…[4 marks]
  4. 2(b)(i)Define the term 'rate of reaction'.[2 marks]
  5. 2(b)(ii)Explain how catalysts and surface area affect the rate of a chemical reaction.[4 marks]
  6. 2(c)(i)Use ONLY the data in Table 4 to determine the order of reaction with respect to S2O8^2- and I^-.[4 marks]
  7. 2(c)(ii)Based on your answer in (c)(i), determine the overall order of the reaction.[1 mark]
  8. 2(c)(iii)Determine the rate law for the reaction.[2 marks]
  9. 2(d)(i)Define the term 'standard electrode potential of a half cell'.[2 marks]
  10. 2(d)(ii)Draw a labelled diagram to show how the standard electrode potential of the Fe3+(aq)/Fe2+(aq) half cell can be determined.[5 marks]

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