Quelpr
3 marksInfrared Spectroscopy

CAPE Chemistry Unit 2 · May/June 2019 · Paper 2 · Question 2(d)(i)

The IR spectra in Figures 3, 4 and 5 belong to the compounds 3-methylbutanol [(CH3)2CHCH2CH2OH], heptanone [CH3CH2CH2CH2CH2COCH3], and methylpentanoate [CH3(CH2)2COOCH3]. Identify EACH of the compounds from the IR spectra provided in Figures 3, 4 and 5. Justify your choice by indicating the band(s) on the spectra used to verify the identity of the compounds and indicate the functional groups responsible for the band(s) in EACH case.

Identify the compound and provide justification for Figure 3.

This question uses a figure or table from the paper — you'll see it when you practise.

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 2(a)State the meaning of EACH of the following terms: Electromagnetic radiation, Wavelength, Frequency.[3 marks]
  2. 2(b)(i)Write the formula which relates the speed of light (c), the wavelength of light (λ) and its frequency (v).[1 mark]
  3. 2(b)(ii)Using the formula from (b) (i), calculate the missing frequencies and wavelengths in Table 2 AND identify the corresponding type of electromagnetic radiation.…[4 marks]
  4. 2(c)(i)Complete Figure 2 by inserting arrows to show ALL possible electron transitions in the molecular orbitals indicated.[3 marks]
  5. 2(c)(ii)List the transitions from (c) (i) which will normally produce absorption in the ultraviolet and visible regions of the electromagnetic spectrum.[3 marks]
  6. 2(c)(iii)The absorbance of an iron thiocyanate solution containing 0.005 mol Fe/mL was reported as 0.4900 at 540 nm. Using Beer–Lambert's law, A = εcl, calculate the…[4 marks]
  7. 2(d)(ii)Identify the compound and provide justification for Figure 4.[2 marks]
  8. 2(d)(iii)Identify the compound and provide justification for Figure 5.[2 marks]
  9. 2(e)(i)Describe FOUR steps to be taken by the student in preparing the sample for analysis.[4 marks]
  10. 2(e)(ii)Give ONE reason why the plates used for IR spectroscopy are made from NaCl.[1 mark]

More practice: the rest of this paper · more Infrared Spectroscopy questions · all CAPE Chemistry Unit 2 past papers