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Question 1
The structure that represents an ester is:
A.
B.
C.
D.
Question 2
A compound has the formula and contains no carbon-carbon multiple bonds.
What homologous series does it belong to?
A.
alkene
B.
alcohol
C.
halogenoalkane
D.
alkyne
Question 3
The skeletal formula of an organic compound is shown.
What is its molecular formula?
A.
B.
C.
D.
Question 4
The boiling points of methanol, ethanol, propan-1-ol and butan-1-ol are compared.
What best explains the trend down this homologous series?
A.
Boiling point increases because covalent bonds within the molecules become stronger.
B.
Boiling point decreases because hydrogen bonding becomes weaker as the chain length increases.
C.
Boiling point increases because longer chains have stronger London dispersion forces.
D.
Boiling point decreases because the molecules become less polar as the chain length increases.
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Question 5
Propan-1-ol and methoxyethane both have the molecular formula .
What is the relationship between these two compounds?
A.
chain isomers
B.
stereoisomers
C.
functional group isomers
D.
position isomers
Question 6
The representation of trans-1,2-dichlorocyclobutane is:
A.
B.
C.
D.
Question 7
The compound that can show cis-trans isomerism is:
A.
but-2-ene
B.
2-methylpropene
C.
but-1-ene
D.
propene
Question 8
An IR spectrum of an organic compound is shown.
What functional group is indicated by the diagnostic absorptions?
A.
alcohol
B.
alkene
C.
carboxylic acid
D.
amine
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Question 9
The skeletal formula of an organic compound is shown.
Determine the molecular formula of the compound.
[1]
State the homologous series to which the compound belongs.
[1]
Write a condensed structural formula for the compound.
[1]
Question 10
Structural isomerism and primary, secondary and tertiary classification are useful when comparing organic compounds.
Define structural isomers.
[1]
Classify as a primary, secondary or tertiary halogenoalkane.
[1]
Name the ketone functional group isomer of propanal.
[1]
Question 11
What is the correct IUPAC name of the compound shown?
A.
2-ethylbutan-4-ol
B.
2-methylpentan-4-ol
C.
4-methylpentan-4-ol
D.
4-methylpentan-2-ol
Question 12
An organic compound has a molecular ion peak at . Its mass spectrum also has a strong fragment peak assigned to .
What structural feature is best supported by this evidence?
A.
a carboxylic acid group
B.
a phenyl group
C.
a primary alcohol group
D.
a ketone carbonyl group
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Question 13
The following compounds contain common functional groups: , and .
State the class of compound represented by .
[1]
Distinguish between the carbonyl groups in and .
[2]
State whether is saturated or unsaturated.
[1]
Question 14
A graph shows the boiling points of the first several straight-chain alcohols plotted against the number of carbon atoms in the molecule.
State the common structural unit by which successive members of this homologous series differ.
[1]
Write the general formula for a saturated monohydric alcohol in this series.
[1]
Explain the trend in boiling point shown by the graph.
[2]
Question 15
IUPAC nomenclature is used to give systematic names to organic compounds.
Name using IUPAC nomenclature.
[1]
Write a condensed structural formula for 2-chloro-3-methylpentane.
[1]
Explain why is named hex-2-ene rather than hex-4-ene.
[2]
Question 16
Displayed formulae of but-2-ene and propene are shown.
State which compound can show cis-trans isomerism.
[1]
Explain why the other compound does not show cis-trans isomerism.
[2]
Draw the trans isomer of but-2-ene.
[1]
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Question 17
A stereochemical formula of 2-bromobutane is shown.
Identify the chiral carbon atom in 2-bromobutane.
[1]
Explain why this carbon atom is chiral.
[2]
State the composition and optical effect of a racemic mixture of 2-bromobutane.
[1]
Question 18
Three representations of organic compounds, labelled A, B and C, are shown.
State the molecular formula of compound B.
[1]
Identify the type of formula used for compound C.
[1]
Use compounds A and C to explain one limitation of using molecular formulas to represent organic compounds.
[2]
Question 19
A student sorted several organic compounds using the functional groups shown in the stimulus.
Identify the functional group present in compound B and the organic class to which B belongs.
[2]
Identify the compound that contains an amido group.
[1]
Distinguish, using the structures, between the aldehyde and ketone compounds in the stimulus.
[2]
Question 20
A compound with molecular formula gives two signals in its NMR spectrum. Both signals are singlets and their integrations are in a ratio. Its IR spectrum contains a strong absorption and no broad absorption.
What is the most likely structure?
A.
B.
C.
D.
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Question 21
A compound has a molecular ion peak at . Its IR spectrum shows a strong absorption and no broad absorption. Its NMR spectrum has one singlet with integration corresponding to six hydrogen atoms.
What structure is consistent with all the evidence?
A.
propanone,
B.
propan-2-ol,
C.
propanal,
D.
methoxyethane,
Question 22
Butane, 2-methylpropane and butan-1-ol all contain four carbon atoms.
State the strongest type of intermolecular force between butan-1-ol molecules.
[1]
Explain why butan-1-ol has a higher boiling point than butane.
[2]
Explain why 2-methylpropane has a lower boiling point than butane.
[1]
Question 23
The mass spectrum of an organic compound with molecular formula has a molecular ion peak at and a strong fragment peak at . The data booklet identifies as possible evidence for .
State what is meant by the molecular ion peak.
[1]
Determine the relative molecular mass of the compound.
[1]
Identify the functional group suggested by the fragment.
[1]
Suggest the structure of the compound.
[1]
Question 24
An infrared spectrum of an organic compound shows a very broad absorption in the O-H region and a strong absorption in the C=O region.
Identify the class of compound most consistent with these two absorptions.
[1]
Explain how the two absorptions support this identification.
[2]
State the condition for a molecular vibration to be IR active.
[1]
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Question 25
A high-resolution NMR spectrum of a compound with molecular formula has three signals. The integrations are 3:2:3. One signal is a singlet, one is a quartet and one is a triplet.
State the number of different hydrogen environments in the compound.
[1]
Use the splitting patterns to identify the hydrocarbon fragment responsible for the quartet and triplet.
[2]
Suggest a structure consistent with these data.
[1]
Question 26
A database entry gives formulas and boiling points for consecutive members of one homologous series.
Number of carbon atoms | Formula | Boiling point / |
|---|---|---|
1 | 64.7 | |
2 | 78.4 | |
3 | 97.2 | |
4 | 117.7 | |
5 | — | 137.9 |
Deduce the missing formula for the member with five carbon atoms.
[1]
Identify the homologous series and give its general formula.
[2]
Explain why members of this series have similar chemical reactions.
[1]
Question 27
The graph compares boiling points of two homologous series with the same number of carbon atoms per molecule. A separate point is plotted for a branched alkane isomer.
Describe the trend in boiling point shown for each homologous series as the number of carbon atoms increases.
[1]
Estimate the difference between the boiling points of the four-carbon alcohol and the four-carbon alkane.
[1]
Explain the difference between the boiling points of the straight-chain four-carbon alkane, the branched alkane isomer and the four-carbon alcohol.
[3]
Question 28
The stimulus shows four organic molecules or pairs of molecules used to investigate stereoisomerism.
Identify the two cases that show cis-trans isomerism.
[1]
Explain why propene does not show cis-trans isomerism.
[2]
State why cis-trans isomers of 1,2-dimethylcyclobutane are configurational isomers rather than conformational isomers.
[1]
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Question 29
Wedge-dash representations and polarimetry data are shown for samples containing stereoisomers of 2-bromobutane.
Identify the chiral carbon atom in 2-bromobutane using the labelled structure.
[1]
Identify the pair of enantiomers from the four wedge-dash structures.
[1]
Explain why a racemic mixture of these enantiomers is optically inactive.
[2]
Question 30
An unknown compound has molecular formula . Its IR spectrum shows a strong absorption in the C=O region and no broad O-H absorption. Its low-resolution NMR spectrum has one signal with integration corresponding to six hydrogen atoms.
Identify the functional group indicated by the IR spectrum.
[1]
Explain what the single NMR signal indicates about the hydrogen atoms.
[1]
Deduce the structure of the compound.
[1]
Explain why propanal is not consistent with the NMR evidence.
[1]
Question 31
Three organic structures, A, B and C, are shown. A proposed IUPAC name is written under compound C.
Give the IUPAC name of compound A.
[2]
Give the IUPAC name of compound B.
[1]
State the error in the proposed name of compound C.
[1]
Question 32
The table shows structural formulas and boiling points for several compounds with molecular formula .
Compound | Structural formula | Boiling point / |
|---|---|---|
butan-1-ol | 117.7 | |
butan-2-ol | 99.5 | |
2-methylpropan-1-ol | 108.0 | |
ethoxyethane | 34.6 |
Identify one pair of functional group isomers from the table.
[1]
Classify butan-2-ol as a primary, secondary or tertiary alcohol. Justify your answer.
[2]
Explain why the ether has a lower boiling point than the straight-chain alcohol with the same molecular formula.
[2]
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Question 33
The mass spectrum of an organic compound X with formula is shown. Selected fragment ions from the data booklet are also provided.
State the relative molecular mass of X from the spectrum.
[1]
Identify the peak that corresponds to the molecular ion.
[1]
Use the fragment peaks to suggest whether X is more likely to be butan-1-ol or ethoxyethane.
[2]
Question 34
Infrared spectra for three compounds, A, B and C, are shown.
Identify the compound that is most likely to be an ester.
[1]
Justify your answer to (a) using two features from the IR spectrum.
[2]
Explain why an IR spectrum can identify functional groups but may not prove the complete structure of an organic compound.
[2]
Question 35
A high-resolution NMR spectrum is shown for a compound with molecular formula .
Signal | Peak range / ppm | Multiplicity | Relative integration (H) |
|---|---|---|---|
1 | 1.20–1.35 | triplet | 3 |
2 | 3.35–3.50 | quartet | 2 |
State the number of different hydrogen environments in the molecule.
[1]
Explain the triplet and quartet splitting pattern using the rule.
[2]
Deduce the structure of the compound.
[1]
Question 36
Compounds A, B and C are represented using different types of organic formula.
Compound A is shown by a condensed structural formula.
I.
State the molecular formula of compound A.
[1]
II.
Identify the class of compound A and state whether the carbon bonded to the functional group is primary, secondary or tertiary.
[1]
Compound B is represented by a skeletal formula.
I.
Explain how the molecular formula of compound B can be obtained from the skeletal formula.
[2]
II.
State whether compound B is saturated or unsaturated, giving a reason.
[1]
Compare the information shown by the structural representation of compound C with its molecular formula.
[2]
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Question 37
The boiling points of several unbranched organic compounds were measured at standard pressure.
Use the data to compare trends in boiling point within and between the two homologous series.
I.
State the trend in boiling point as the number of carbon atoms increases within each series.
[1]
II.
Compare the boiling points of alcohols with those of alkanes containing the same number of carbon atoms.
[1]
Explain the trend in boiling point within the alkane series.
[2]
Explain why ethanol has a much higher boiling point than ethane even though their molar masses are similar.
[2]
Suggest one reason why extrapolating the graph far beyond the measured carbon chain lengths may give unreliable boiling point predictions.
[1]
Question 38
A molecule used as a local anaesthetic is shown. It contains several functional groups.
Identify three functional groups present in the molecule.
I.
State the name of the aromatic substituent present.
[1]
II.
State the name of the functional group containing both a carbonyl bond and an oxygen atom bonded to another carbon atom.
[1]
III.
State the name of the nitrogen-containing functional group shown as bonded to carbon.
[1]
Explain why identifying functional groups is useful when predicting the properties of an organic compound.
[2]
State whether the molecule is saturated or unsaturated, giving a reason.
[1]
Question 39
Several compounds with the molecular formula are shown.
Classify the structural isomerism shown by pairs of the compounds.
I.
State the type of structural isomerism between A and B.
[1]
II.
State the type of structural isomerism between A and C.
[1]
III.
State the type of structural isomerism between A and D.
[1]
Explain how primary, secondary and tertiary alcohols are distinguished, using compounds A, B and C as examples.
[3]
Suggest why compounds A and D can have different chemical properties despite having the same molecular formula.
[1]
Question 40
Spectroscopic data are shown for an unknown organic compound Y. Elemental analysis gives the molecular formula .
Technique | Observed peaks / units |
|---|---|
IR | 1740 (strong, sharp); 1240 (strong) |
Mass spectrum | 74 (, weak); 43 (base peak) |
H NMR | 2.1 (singlet, 3H); 3.7 (singlet, 3H) |
Use the IR spectrum to identify the functional group class most consistent with Y.
[1]
Use the mass spectrum to state the relative molecular mass of Y and identify the fragment at .
[2]
Deduce the structure of Y and justify it using the NMR data.
[2]
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Question 41
Four students proposed IUPAC names for different compounds containing one type of functional group.
Name compounds A and B using IUPAC nomenclature.
I.
Give the IUPAC name of compound A.
[2]
II.
Give the IUPAC name of compound B.
[2]
A student names compound C as 2-ethylpropanal. Evaluate this name and give the correct IUPAC name.
[2]
Compound D has the molecular formula .
I.
Give the IUPAC name of compound D.
[1]
II.
Explain why no locant is needed for the carboxyl group in the name of compound D.
[1]
Question 42
A student is given three unknown acyclic hydrocarbons, X, Y and Z. Assume that the three hydrocarbons are one alkane, one alkene and one alkyne. Their molecular formulas are , and respectively.
Use general formulas to classify the three hydrocarbons.
I.
Classify X and give the relevant general formula.
[1]
II.
Classify Y and give the relevant general formula.
[1]
III.
Classify Z and give the relevant general formula.
[1]
Draw a possible structural formula for Y and name it.
[2]
Explain why successive members of one homologous series differ by but have similar chemical reactions.
[1]
Question 43
Stereoisomerism can occur in alkenes, cycloalkanes and molecules containing a chiral carbon atom.
Compound A is one stereoisomer of but-2-ene.
I.
State whether A is the cis or trans isomer.
[1]
II.
Explain why but-2-ene shows cis-trans isomerism but propene does not.
[1]
Compound B is a stereoisomer of 1,2-dimethylcyclopropane.
[2]
Compound C is shown below.
I.
State whether compound C contains a chiral carbon atom.
[1]
II.
Explain why compound C does not have enantiomers.
[2]
Question 44
Compounds X and Y are structural isomers with molecular formula . Their mass spectra both contain a molecular ion peak, but their fragmentation patterns are different.
Use the molecular ion peak to determine information about X and Y.
I.
State the value expected for the molecular ion peak of both compounds.
[1]
II.
Explain why the molecular ion peak alone cannot distinguish X from Y.
[1]
Compound X shows a strong peak at and a peak at . Explain how these peaks support the structure butan-2-ol rather than ethoxyethane.
[3]
Compound Y shows strong peaks at and .
I.
Suggest a fragment ion responsible for the peak at .
[1]
II.
Explain why the peaks at and are consistent with cleavage adjacent to the oxygen atom in ethoxyethane.
[1]
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Question 45
Infrared spectra of three organic compounds, P, Q and R, are shown in the functional group region. Each compound contains carbon, hydrogen and oxygen only.
Interpret the spectra of P and Q using the functional group region.
I.
Identify the functional group in P responsible for the broad absorption in the range about -.
[1]
II.
Explain why Q is more likely to be a carboxylic acid than an ester.
[2]
Compound R has molecular formula . Evaluate whether the IR evidence is consistent with R being an ester.
[2]
IR spectroscopy is also relevant to atmospheric chemistry.
I.
State the condition required for a molecular vibration to be IR active.
[1]
II.
Explain why some greenhouse gases absorb outgoing infrared radiation from Earth.
[1]
Question 46
An unknown compound, M, has molecular formula . Its IR spectrum shows a strong absorption at about and no broad absorption above . Its NMR spectrum is summarized below.
Chemical shift / ppm | Integration / H | Multiplicity |
|---|---|---|
4.12 | 2 | quartet |
2.05 | 3 | singlet |
1.26 | 3 | triplet |
Use the IR evidence to narrow down the possible functional groups in M.
I.
Identify the bond responsible for the strong absorption at about .
[1]
II.
Explain why the absence of a broad absorption above helps rule out a carboxylic acid.
[1]
Interpret the NMR data.
[4]
Deduce the structure of M and justify why one other isomer with formula is unsuitable.
I.
Draw the structural formula of M.
[1]
II.
Explain why butanoic acid is not consistent with the spectroscopic evidence.
[1]
Question 47
High-resolution NMR spectra can distinguish structural isomers by their splitting patterns. Two isomeric compounds, A and B, have molecular formula .
Compound | / ppm | Integration / H | Multiplicity |
|---|---|---|---|
A | 0.9 | 3 | triplet |
A | 1.7 | 2 | multiplet |
A | 3.4 | 2 | triplet |
B | 1.7 | 6 | doublet |
B | 4.2 | 1 | multiplet |
The spectrum of B contains a doublet integrating to six hydrogens and a multiplet integrating to one hydrogen.
I.
Explain why the six hydrogen signal is a doublet.
[1]
II.
Deduce the structure of B.
[1]
III.
Explain why B has only two proton environments.
[1]
Compound A is the other structural isomer, 1-bromopropane. Predict features of its NMR spectrum.
[3]
Evaluate the usefulness of splitting patterns compared with integration data for distinguishing A and B.
I.
State one piece of integration evidence that distinguishes A from B.
[1]
II.
Explain one additional structural detail provided by splitting patterns.
[1]
Question 48
An unknown liquid, Z, contains only carbon, hydrogen and oxygen. Combustion analysis gives the empirical formula . The mass spectrum, IR spectrum and NMR spectrum are used together to determine its structure.
Evidence | Observed data |
|---|---|
Combustion analysis | Empirical formula: |
Mass spectrum | at m/z 116; prominent fragments at m/z 43 and 57 |
IR spectrum | Strong absorption at ; no broad absorption from - |
1H NMR spectrum | 2.12 (s, 3H) and 1.28 (s, 9H) |
Use the empirical formula and molecular ion peak.
I.
Calculate the empirical formula mass of .
[1]
II.
The molecular ion peak is at . Deduce the molecular formula of Z.
[1]
Use the IR and mass spectrum evidence to evaluate possible functional groups.
[3]
The NMR spectrum of Z contains two singlets with integrations of 3H and 9H.
I.
Explain what the two singlets with integrations of 3H and 9H show about the hydrogen environments in Z.
[2]
II.
Deduce a structure for Z consistent with all the evidence.
[1]
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