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Date	May 2019	Marks available	1	Reference code	19M.1.hl.TZ2.40
Level	HL	Paper	1	Time zone	TZ2
Command term		Question number	40	Adapted from	N/A

Question

Which technique involves breaking covalent bonds when carried out on an organic compound?

A. infrared spectroscopy

B. nuclear magnetic resonance spectroscopy

C. X-ray crystallography

D. mass spectrometry

Markscheme

Examiners report

This question challenged candidates to think about analytical techniques more deeply. 67 % of the candidates recognized that mass spectrometry involves breaking covalent bonds. The most commonly chosen distractor was X-ray crystallography (option C).

Syllabus sections

Core » Topic 11: Measurement and data processing » 11.3 Spectroscopic identification of organic compounds

Show 80 related questions

18M.1.sl.TZ1.29: What is the index of hydrogen deficiency, IHD, of 3-methylcyclohexene? A. 0 B. ...
18M.1.sl.TZ1.30: What is the ratio of the areas of the signals in the 1H NMR spectrum of pentan-3-ol? A. ...
18M.2.sl.TZ1.1i:
Predict the number of signals in the ¹H NMR spectrum of urea.
18M.1.sl.TZ2.28: Which feature of a molecule does infrared spectrometry detect? A. molecular mass B. ...
18M.2.sl.TZ2.7c.i:
Deduce the molecular formula of the compound.
18M.3.sl.TZ2.7b:
Deduce the number of ¹H NMR signals produced by the zwitterion form of alanine.
17N.3.hl.TZ0.22a.i: Both spectra show a peak at wavenumber 1700 cm–1. Identify the bond responsible for this peak.
22M.1.sl.TZ1.30:
What is the index of hydrogen deficiency (IHD) of this molecule?

Paracetamol (acetaminophen)

A. 3

B. 4

C. 5

D. 6
22M.1.sl.TZ1.29:
Which compound produces this mass spectrum?

^{[Spectral Database for Organic Compounds, SDBS. SDBS Compounds and Spectral Search. [graph] Available at:}
^{https://sdbs.db.aist.go.jp [Accessed 3 January 2019].]}
16N.1.sl.TZ0.29: What is always correct about the molecular ion, M+, in a mass spectrum of a compound? A. The...
22M.1.sl.TZ2.28: How many signals are observed in the 1H NMR spectrum of this compound?A. 1 B. 2 C. 3 D. 4
22M.1.hl.TZ2.40:
Given equimolar concentrations, which substance would produce the strongest signal in a ¹H NMR spectrum?

A. (CH₃)₃CH

B. C₆H₆

C. C₈H₁₈

D. Si(CH₃)₄
17M.1.sl.TZ2.28:
Which information can be gained from an infrared (IR) spectrum?

A. Ionization energy of the most abundant element

B. Number of different elements in the compound

C. Bonds present in a molecule

D. Molecular formula of the compound
17M.1.hl.TZ1.40:
Which technique is used to determine the bond lengths and bond angles of a molecule?

A. X-ray crystallography

B. Infrared (IR) spectroscopy

C. Mass spectroscopy

D. ¹H NMR spectroscopy
17M.1.sl.TZ2.29:
What can be deduced from the following ¹H $\,$ NMR spectrum?

A. There is only one hydrogen atom in the molecule.

B. There is only one hydrogen environment in the molecule.

C. The molecule is a hydrocarbon.

D. There is only one isotope in the element.
17M.3.hl.TZ1.25c:
Organic molecules can be characterized using infrared (IR) spectroscopy.

Compare and contrast the infrared peaks above 1500 cm⁻¹ in pure samples of aspirin and salicylic acid using section 26 of the data booklet.
18M.2.sl.TZ1.1g:
The mass spectrum of urea is shown below.

Identify the species responsible for the peaks at m/z = 60 and 44.
18M.2.sl.TZ2.7c.iii:
Deduce full structural formulas of two possible isomers of the unknown compound, both of which are esters.
18M.2.hl.TZ1.1l.i:
Predict the number of signals in the ¹H NMR spectrum of urea.
18M.2.hl.TZ1.1k:
The IR spectrum of urea is shown below.

Identify the bonds causing the absorptions at 3450 cm⁻¹ and 1700 cm⁻¹ using section 26 of the data booklet.
21N.1.sl.TZ0.5: Consider the mass spectrum of an element: What is the relative atomic mass of this...
18N.1.sl.TZ0.29: What is the ratio of areas under each signal in the 1H NMR spectrum of...
18N.1.sl.TZ0.28: Which is correct for the spectra of organic compounds? A. Mass spectroscopy provides...
18N.2.hl.TZ0.2c: The mass spectrum of the compound is shown. Deduce the relative molecular mass of the...
18N.2.hl.TZ0.2b: The infrared spectrum of the compound is shown. Deduce the functional group of the compound.
19M.1.hl.TZ2.39:
What can be deduced from the infrared (IR) spectrum of a compound?

A. Number of hydrogens

B. Number of hydrogen environments

C. Bonds present

D. Molar mass
17N.3.hl.TZ0.22a.ii:
Deduce which spectrum belongs to paracetamol, giving two reasons for your choice. Use section 26 of the data booklet.
19M.2.sl.TZ2.1c(v):
The IR spectrum and low resolution ¹H NMR spectrum of the actual product formed are shown.

Deduce whether the product is A or B, using evidence from these spectra together with sections 26 and 27 of the data booklet.

Identity of product:

One piece of evidence from IR:

One piece of evidence from ¹H NMR:
19M.3.hl.TZ2.5b:
The infrared (IR) spectrum of polyethene is given.

Suggest how the IR spectrum of polychloroethene would diff er, using section 26 of the data booklet.
17M.3.sl.TZ2.4:
Infrared (IR) spectra can be used to distinguish between various types of plastics. Some simplified IR spectra are given here.

Explain, with a reference to molecular structure, which two of the plastics can not be distinguished by IR spectroscopy.
19M.3.sl.TZ2.5b:
The infrared (IR) spectrum of polyethene is given.

Suggest how the IR spectrum of polychloroethene would differ, using section 26 of the data booklet.
19M.1.sl.TZ2.30:
What can be deduced from the infrared (IR) spectrum of a compound?

A. Number of hydrogens

B. Number of hydrogen environments

C. Bonds present

D. Molar mass
19M.1.sl.TZ1.30:
What is the degree of unsaturation (index of hydrogen deficiency) for the molecule?

A. 1

B. 2

C. 4

D. 5
17M.2.sl.TZ2.8c:
Identify the highest m/z value in the mass spectrum of quinone.
17N.1.sl.TZ0.29:
What information is provided by ¹H NMR, MS and IR for an organic compound?

I. ¹H NMR: chemical environment(s) of protons
II. MS: fragmentation pattern
III. IR: types of functional group

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
17N.3.sl.TZ0.7b.ii:
One of the two infrared (IR) spectra is that of polyethene and the other of polytetrafluoroethene (PTFE).

Deduce, with a reason, which spectrum is that of PTFE. Infrared data is given in section 26 of the data booklet.
18M.2.sl.TZ2.7c.ii:
Identify the bonds causing peaks A and B in the IR spectrum of the unknown compound using section 26 of the data booklet.
19M.2.hl.TZ1.1a:
State the number of ¹H NMR signals for this isomer of xylene and the ratio in which they appear.
17M.2.sl.TZ2.8b:
Identify the species responsible for the peak at m/z = 110 in the mass spectrum of hydroquinone.
17M.3.sl.TZ1.10a:
Below are the IR spectra of two plastics (A and B); one is PETE, the other is low density polyethene (LDPE).

Deduce, giving your reasons, the identity and resin identification code (RIC) of A and B using sections 26 and 30 of the data booklet.
16N.1.sl.TZ0.28:
What is the index of hydrogen deficiency (IHD) for this molecule?

A. 3

B. 4

C. 5

D. 6
17M.1.sl.TZ1.30:
What is the Index of Hydrogen Deficiency (IHD) for 1,3,5-hexatriene (C₆H₈)?

A. 1

B. 3

C. 5

D. 6
17M.3.hl.TZ2.21c.i:
Predict the number of different hydrogen environments in the molecule ignoring the benzene rings.
18M.2.hl.TZ1.1j:
The mass spectrum of urea is shown below.

Identify the species responsible for the peaks at m/z = 60 and 44.
17N.2.sl.TZ0.6a.iii: Deduce the number of signals and the ratio of areas under the signals in the 1H NMR spectra...
19N.2.hl.TZ0.3d(iii):
Explain why the ¹H NMR spectrum of C₃H₆O, produced in (d)(i), shows only one signal.
19N.3.sl.TZ0.12b(ii): The 1H NMR spectrum of one of the products has four signals. The integration trace shows a...
17M.1.sl.TZ1.28:
What can be determined about a molecule from the number of signals in its ¹H $\,$ NMR spectrum?

A. Bonds present

B. Molecular formula

C. Molecular mass

D. Number of hydrogen environments
17M.3.sl.TZ1.19d:
Organic molecules can be characterized using infrared (IR) spectroscopy.

Compare and contrast the infrared peaks above 1500 cm⁻¹ in pure samples of aspirin and salicylic acid using section 26 of the data booklet.
21N.1.sl.TZ0.30:
What can be deduced from the mass spectrum of CH₃COCH₂CH₂CH₃?

NIST Mass Spectrometry Data Center Collection (C) 2021 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. 2-Pentanone Mass Spectrum, MS Number 291264. [graph] Available at: https://webbook.nist.gov/cgi/cbook.cgi?ID=C107879&Units=SI&Mask=200#Mass-Spec2-pentanone [Accessed 4 May 2020]. source adapted.

A. The molar mass is 43 g mol⁻¹.

B. The atoms have many isotopes.

C. The most likely bond to break is C–C between carbons 2 and 3.

D. The signal with the largest mass is due to the oxidation of the ketone in the spectrometer.
21N.2.hl.TZ0.1c:
Identify each compound from the spectra given, use absorptions from the range of 1700 cm⁻¹ to 3500 cm⁻¹. Explain the reason for your choice, referring to section 26 of the data booklet.
17M.2.hl.TZ2.7a.i:
Deduce what information can be obtained from the ¹H NMR spectrum.
20N.1.sl.TZ0.29:
What is the index of hydrogen deficiency (IHD) in cyclohexanol?

A.   $0$

B.   $1$

C.   $2$

D.   $3$
19M.2.sl.TZ1.1a:
State the number of 1H NMR signals for this isomer of xylene and the ratio in which they appear.

Number of signals:

Ratio:
17M.2.hl.TZ2.7a.ii:
Identify the functional group that shows stretching at 1710 cm^–1 in the infrared spectrum of this compound using section 26 of the data booklet and the ¹H NMR.
20N.1.sl.TZ0.30: Which region of the electromagnetic spectrum is used to identify hydrogen environments in a...
18M.2.sl.TZ1.1h:
The IR spectrum of urea is shown below.

Identify the bonds causing the absorptions at 3450 cm⁻¹ and 1700 cm⁻¹ using section 26 of the data booklet.
20N.2.hl.TZ0.1d(v):
Deduce the number of signals and chemical shifts with splitting patterns in the ¹H NMR spectrum of ethoxyethane. Use section 27 of the data booklet.
18M.2.sl.TZ2.7c.iv:
Deduce the formula of the unknown compound based on its ¹H NMR spectrum using section 27 of the data booklet.
17M.3.hl.TZ2.20a.iii:
Suggest two absorbances, other than the absorbances due to the ring structure and C–H bonds, that would be present in the infrared (IR) spectrum of aspirin.
21M.1.sl.TZ1.30:
Determine the index of hydrogen deficiency (IHD) of paracetamol.

A. 3

B. 4

C. 5

D. 6
21N.2.sl.TZ0.1c:
Identify each compound from the spectra given, use absorptions from the range of 1700 cm⁻¹ to 3500 cm⁻¹. Explain the reason for your choice, referring to section 26 of the data booklet.
21M.2.hl.TZ1.5b(i): Justify why ethene has only a single signal in its 1H NMR spectrum.
21M.1.sl.TZ2.28:
Which spectra would show the difference between propan-2-ol, CH₃CH(OH)CH₃, and propanal, CH₃CH₂CHO?

I. mass
II. infrared
III. ¹H NMR

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
17M.3.sl.TZ2.18a.ii:
Deduce the wavenumber of one absorbance seen in the IR spectrum of only one of the compounds, using section 26 of the data booklet.
21M.2.sl.TZ1.5b: Justify why ethene has only a single signal in its 1H NMR spectrum.
21M.2.sl.TZ2.4e(i): Deduce two features of this molecule that can be obtained from the mass spectrum. Use section...
21M.2.sl.TZ2.4e(iii):
Deduce the identity of the unknown compound using the previous information, the ¹H NMR spectrum and section 27 of the data booklet.

SDBS, National Institute of Advanced Industrial Science and Technology (AIST).
21M.2.sl.TZ2.4e(ii): Identify the bond responsible for the absorption at A in the infrared spectrum. Use section...
21M.2.hl.TZ2.4g(iii):
Deduce the identity of the unknown compound using the previous information, the ¹H NMR spectrum and section 27 of the data booklet.

SDBS, National Institute of Advanced Industrial Science and Technology (AIST).
21M.2.hl.TZ2.4g(i): Deduce two features of this molecule that can be obtained from the mass spectrum. Use section...
21M.2.hl.TZ2.4g(ii): Identify the bond responsible for the absorption at A in the infrared spectrum. Use section...
20N.2.hl.TZ0.2d:
The IR spectrum of one of the compounds is shown:

COBLENTZ SOCIETY. Collection © 2018 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Deduce, giving a reason, the compound producing this spectrum.
20N.2.sl.TZ0.2b:
The IR spectrum of one of the compounds is shown:

COBLENTZ SOCIETY. Collection © 2018 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Deduce, giving a reason, the compound producing this spectrum.
20N.2.sl.TZ0.1d(vi):
Deduce the number of signals and their chemical shifts in the ${}_{1}H NMR$ spectrum of ethoxyethane. Use section 27 of the data booklet.
22M.2.hl.TZ2.8d(iv):
Suggest two differences in the ¹H NMR of but-2-ene and the organic product from (d)(ii).
22M.2.sl.TZ2.4d(iv):
Suggest two differences in the ¹H NMR of but-2-ene and the organic product from (d)(ii).
17M.2.hl.TZ1.6c.ii:
The mass and ¹H NMR spectra of product X are shown below. Deduce, giving your reasons, its structural formula and hence the name of the compound.
17M.2.sl.TZ1.5c.ii:
The mass and ¹H $\,$ NMR spectra of product X are shown below. Deduce, giving your reasons, its structural formula and hence the name of the compound.
21N.2.hl.TZ0.1e: Predict the fragment that is responsible for a m/z of 31 in the mass spectrum of propan‑1‑ol....

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