DP IB Chemistry: HL

Topic Questions

IBChemistry: HLDPTopic Questions21. Measurement & Analysis (HL only)21.1 Spectroscopic Identification of Organic compounds

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First teaching 2014

Last exams 2024

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21.1 Spectroscopic Identification of Organic compounds

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1
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Which of the following pieces of information can X-ray crystallography not give directly?

  • The location of individual atoms 

  • Internuclear distances

  • The identity of individual atoms

  • Bond angles

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2
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The IUPAC name of mellitene, C6(CH3)6, is 1,2,3,4,5,6-hexamethylbenzene.

What splitting pattern will be seen on the 1H NMR spectrum for mellitene?

  • Singlet

  • Doublet

  • Triplet

  • Quartet

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3
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Using the mass spectrum below, what is the molecular ion peak of 2-methylbutane?

lOR_1t2E_2-methylbutane-mass-spectrum

  • 29

  • 43

  • 57

  • 72

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4
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Which of the following chemicals has a singlet peak in its 1H NMR spectrum?

  1. propan-2-yl-ethanoate

  2. 2-chloropropane

  3. butyl-ethanoate

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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5
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The structure of 2-chloropropane is shown below. 

2-chloropropane

Which description of the peaks in the 1H NMR spectrum of 2-chloropropane is correct?

  • 1 peak with a relative intensity of 6

  • 2 peaks with relative intensities of 3 : 4

  • 2 peaks with relative intensities 6 : 1

  • 3 peaks with relative intensities of 3 : 1 : 3

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1
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The structure of 2-methylbutan-2-yl 2-methylpropanoate is shown below.

2-methylbutan-2-yl-2-methylpropanoate

How many signals would be found in the 1H NMR spectrum of 2-methylbutan-2-yl 2-methylpropanoate and what would be the ratio of the peak areas?

  Signals Ratio of peak areas
A 3 2 : 2 : 1
B 4 6 : 6 : 3 : 2
C 5 6 : 6 : 3 : 2 : 1
D 5 3 : 3 : 3 : 2 : 1

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2
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Which benzene derivative is represented by the following electron density map?

bromobenzene-electron-density-map

  • Benzaldehyde

  • Benzoic acid

  • Bromobenzene

  • Nitrobenzene

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3
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Which of the following statements about angelic acid are correct?

angelic-acid

  1. The IUPAC name of angelic acid is (E)-2-methyl-2-butenoic acid
  2. Its 1H NMR spectrum contains a quartet peak
  3. It has a molecular ion peak at m/e = 100.13

  • I and II only 

  • I and III only 

  • II and III only 

  • I, II and III 

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4
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Which compound(s) produces the fewest number of peaks in its 1H NMR spectrum?

I II III
1-2-dimethylbenzene 1-2-dimethylcyclopentane 2-methylpropanal
1,2-Dimethylbenzene 1,2-dimethylcyclopentane 2-methylpropanal

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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5
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The 1H NMR spectrum of CH3CHCl2 shows two signals.

What is the correct assignment of splitting patterns for these signals?

  CH3 group CH group
A doublet quartet
B quartet doublet
C singlet singlet
D triplet singlet

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11 mark

Which spectroscopic technique can be used to determine bond length and angles?

  • Mass spectroscopy

  • IR spectroscopy

  • X-ray diffraction

  • 1H NMR spectroscopy

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21 mark

Which row correctly describes the splitting pattern observed on the 1H NMR spectrum for each labelled hydrogen?


q2_21-1_spectroscopic-identification-of-organic-compounds_medium_ib_hl

  • One doublet and four triplets

  • One triplet, one quartet and one singlet

  • One triplet, one doublet and three singlets

  • One triplet, one quartet and three singlets

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31 mark

Tetramethylsilane(TMS) is used as a reference standard in 1H NMR spectroscopy. Which property makes it suitable as a reference standard?

  • It is highly reactive

  • It has no isomers

  • It has 12 identical protons

  • It has a high boiling point

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41 mark

Which of the following produces three peaks in an 1H NMR spectrum? 

  1. CH3COCH2CH3
  2. C6H5NO2
  3. CH3CH2OH

  • I and II only

  • I and III only

  • II and III only 

  • I, II and III

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51 mark

Which molecule could give this NMR spectrum?

q5_21-1_ib_hl_medium_mcq

  • CH3CH2OCH2CH3

  • CH3CH(OH)CH2CH3

  • CH3COCH2CH3

  • CH3COCH2CH2CH3

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