Syllabus Edition
First teaching 2023
First exams 2025
Which of the following statements about propanal, CH3CH2CHO, and propanone, CH3COCH3 is not correct?
The compounds have:
Molecular ion peaks at different mass to charge ratios.
Different fragmentation patterns in the mass spectrum.
Absorption in the infrared spectrum due to the carbonyl group.
A different fingerprint region in the infrared spectrum.
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Which of the following cannot be obtained from an infrared spectrum?
The molecular mass
The presence of C=O bonds
The presence of O-H bonds
The identity of a compound through comparison with other spectra
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The infrared spectrum of a compound is shown below.
Use the infrared absorptions, in wavenumbers, to identify which organic functional group could have produced the infrared spectrum.
|
Bond |
Wavenumber range / cm-1 |
|
C=O (aldehyde or ketone) C=O (carboxylic acids) |
1670 - 1740 1680 - 1730 |
|
C−H (aldehyde) |
2700 - 2775 and 2820 – 2900 |
|
C−H (alkane) |
2850 - 2950 |
|
O−H (carboxylic acids) O−H (alcohol) |
2500 - 3000 3200 – 3600 |
An aldehyde
An alcohol
A carboxylic acid
A ketone
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The infrared spectrum of a compound is shown below.
Use the infrared absorptions, in wavenumbers, to identify the compound.
|
Bond |
Wavenumber range / cm-1 |
|
O−H (alcohol) |
3200 - 3600 |
|
C−H (alkane) |
2850 - 2950 |
|
C−H (aldehyde) |
2700 - 2775 and 2820 - 2900 |
|
C=O (aldehyde or ketone) |
1670 - 1740 |
Which compound is shown by the infrared spectrum?
Propan-1-ol
Propan-2-ol
Propanal
Propanone
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The infrared spectrum of a compound is shown below.
Use the infrared absorptions, in wavenumbers, to identify the compound.
|
Bond |
Wavenumber range / cm-1 |
|
O−H (alcohol) |
3200 - 3600 |
|
C−H (alkane) |
2850 - 2950 |
|
C−H (aldehyde) |
2700 - 2775 and 2820 - 2900 |
|
C=O (aldehyde or ketone) |
1670 - 1740 |
|
C=C |
1500 - 1600 |
Which compound is shown by the infrared spectrum?
Butanoic acid
Butanal
But-1-ene
Butan-1-ol
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The infrared spectrum of a compound is shown below.
Use the infrared absorptions, in wavenumbers, to identify which type of compound does not contain the functional group shown by the infrared spectrum.
|
Bond |
Wavenumber range / cm-1 |
|
O−H (alcohol) |
3200 - 3600 |
|
C−H (alkane) |
2850 - 2950 |
|
C−H (aldehyde) |
2700 - 2775 and 2820 - 2900 |
|
C=O (aldehyde or ketone) |
1670 - 1740 |
|
C=C |
1500 - 1600 |
carboxylic acid
alcohol
ketone
aldehyde
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The infrared spectrum below shows an unknown compound.
|
Bond |
Wavenumber range / cm-1 |
|
C−O; hydroxyl, ester |
1040 – 1300 |
|
C═C; aromatic compound, alkene |
1500 - 1680 |
|
C═O amide carbonyl, carboxyl ester |
1640 – 1690 1670 – 1740 1710 - 1750 |
|
C≡N; nitrile |
2200 – 2250 |
|
C−H; alkane |
2850 – 2950 |
|
N−H; amine, amide |
3300 – 3500 |
|
O−H; carboxyl hydroxyl |
2500 – 3000 3200 - 3600 |
Which compound could have produced the infrared spectrum?
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The diagram shows an infrared spectrum of a compound.
|
Bond |
Wavenumber range / cm-1 |
|
C−O; hydroxyl, ester |
1040 – 1300 |
|
C═C; aromatic compound, alkene |
1500 - 1680 |
|
C═O amide carbonyl, carboxyl ester |
1640 – 1690 1670 – 1740 1710 - 1750 |
|
C≡N; nitrile |
2200 – 2250 |
|
C−H; alkane |
2850 – 2950 |
|
N−H; amine, amide |
3300 – 3500 |
|
O−H; carboxyl hydroxyl |
2500 – 3000 3200 - 3600 |
Which compound would give this spectrum?
Butanoic acid
Butanal
Butan-1-ol
1-bromobutane
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Which of the following infrared spectra could show a carboxylic acid?
|
Bond |
Wavenumber range / cm-1 |
|
C−O; hydroxyl, ester |
1040 – 1300 |
|
C═C; aromatic compound, alkene |
1500 - 1680 |
|
C═O amide carbonyl, carboxyl ester |
1640 – 1690 1670 – 1740 1710 - 1750 |
|
C≡N; nitrile |
2200 – 2250 |
|
C−H; alkane |
2850 – 2950 |
|
N−H; amine, amide |
3300 – 3500 |
|
O−H; carboxyl hydroxyl |
2500 – 3000 3200 - 3600 |
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