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4 marksTitrimetric (Volumetric) Methods of Analysis

CAPE Chemistry Unit 2 · May/June 2024 · Paper 2 · Question 2(c)(vi)

Acetylsalicylic acid (aspirin) concentration was determined by titrating a stock solution (from 10 tablets dissolved in 250 cm³) with standard NaOH. 25.0 cm³ of the solution was titrated. Figure 3 shows the reaction, and Table 1 outlines two titration options.

Given that the stock solution of 250 cm³ contained ten tablets, use the information in (c) (v) to calculate the number of milligrams of aspirin contained in a titrated volume of 25.0 cm³ of aspirin (MW = 180.06 g/mol).

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Other parts of this question

  1. 2(a)(i)Give the name of EACH radiation type: A[1 mark]
  2. 2(a)(ii)Give the name of EACH radiation type: B[1 mark]
  3. 2(a)(iii)Give the name of EACH radiation type: C[1 mark]
  4. 2(a)(iv)Give the name of EACH radiation type: D[1 mark]
  5. 2(b)(i)Calculate the wavelength, λ, in metres (m), for this radiation.[3 marks]
  6. 2(b)(ii)With reference to Figure 2, in what radiation band does the calculated wavelength in (b) (i) belong?[1 mark]
  7. 2(b)(iii)A lamp with filament made from the sample emits light of the same wavelength, λ, obtained in (b) (i). Calculate the energy of a single emitted photon.[3 marks]
  8. 2(c)(i)State which acid would be appropriate to use in Option 1.[1 mark]
  9. 2(c)(ii)In the space below, draw the titration curve that would be obtained for Option 1.[3 marks]
  10. 2(c)(iii)In the space below, draw the titration curve that would be obtained for Option 2.[3 marks]
  11. 2(c)(iv)Using the information in Table 2 below, select the indicator(s) that cannot be used for the titrations. Option 1. Reason for selection. Option 2. Reason for…[4 marks]
  12. 2(c)(v)The titration results obtained from Option 2 are listed below. Complete the table by filling in the spaces.[2 marks]
  13. 2(c)(vii)The ingredient table below lists the milligram quantities of aspirin in a single tablet. Based on the findings in (c) (vi), state whether the information in…[2 marks]

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