DP Chemistry Questionbank

What is the index of hydrogen deficiency (IHD) for this molecule? 

A. 3

B. 4

C. 5

D. 6 

What is the Index of Hydrogen Deficiency (IHD) for 1,3,5-hexatriene (C₆H₈)?

A.     1

B.     3

C.     5

D.     6

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

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.

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

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.

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.

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.

Identify the highest m/z value in the mass spectrum of quinone.

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

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.

Identify the species responsible for the peak at m/z = 110 in the mass spectrum of hydroquinone.

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.

Deduce what information can be obtained from the ¹H NMR spectrum.

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.

Predict the number of different hydrogen environments in the molecule ignoring the benzene rings.

Deduce the wavenumber of one absorbance seen in the IR spectrum of only one of the compounds, using section 26 of the data booklet.

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.

What is the index of hydrogen deficiency (IHD) in cyclohexanol?

A.  $0$

B.  $1$

C.  $2$

D.  $3$

Deduce the number of signals and their chemical shifts in the ${}_1\mathrm{H} \mathrm{NMR}$ spectrum of ethoxyethane. Use section 27 of the data booklet.

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.

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.

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.

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

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.

Deduce which spectrum belongs to paracetamol, giving two reasons for your choice. Use section 26 of the data booklet.

Determine the index of hydrogen deficiency (IHD) of paracetamol.

A.  3

B.  4

C.  5

D.  6

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

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).

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).

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.

The mass spectrum of urea is shown below.

Identify the species responsible for the peaks at m/z = 60 and 44.

Predict the number of signals in the ¹H NMR spectrum of urea.

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.

The mass spectrum of urea is shown below.

Identify the species responsible for the peaks at m/z = 60 and 44.

Predict the number of signals in the ¹H NMR spectrum of urea.

Deduce the molecular formula of the compound.

Identify the bonds causing peaks A and B in the IR spectrum of the unknown compound using section 26 of the data booklet.

Deduce full structural formulas of two possible isomers of the unknown compound, both of which are esters.

Deduce the formula of the unknown compound based on its ¹H NMR spectrum using section 27 of the data booklet.

Deduce the number of ¹H NMR signals produced by the zwitterion form of alanine.

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.

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.

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.

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].]}

What is the index of hydrogen deficiency (IHD) of this molecule?

Paracetamol (acetaminophen)

A.  3

B.  4

C.  5

D.  6

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.

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

Suggest two differences in the ¹H NMR of but-2-ene and the organic product from (d)(ii).

Suggest two differences in the ¹H NMR of but-2-ene and the organic product from (d)(ii).

State the number of ¹H NMR signals for this isomer of xylene and the ratio in which they appear.

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.

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

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

State the number of 1H NMR signals for this isomer of xylene and the ratio in which they appear.

Number of signals:

Ratio:

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:

The infrared (IR) spectrum of polyethene is given.

Suggest how the IR spectrum of polychloroethene would differ, using section 26 of the data booklet.

What is the degree of unsaturation (index of hydrogen deficiency) for the molecule?

A. 1

B. 2

C. 4

D. 5

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

Explain why the ¹H NMR spectrum of C₃H₆O, produced in (d)(i), shows only one signal.