Exam code: 7405
Which statements about alkenes are correct?
| They are less reactive than alkanes towards electrophiles | They are used as monomers for polymerisation | They are formed when larger alkanes are cracked |
A | ✓ | ✓ | ✓ |
B | ✓ | ✓ | ⨯ |
C | ⨯ | ✓ | ✓ |
D | ⨯ | ⨯ | ✓ |
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When bromine reacts with propene in an organic solvent at room temperature, what is the mechanism by which the bromine attacks the propene?
Electrophilic addition
Electrophilic substitution
Nucleophilic addition
Nucleophilic substitution
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Which statements about alkanes and alkenes are correct?
| Bromine reacts with alkanes by electrophilic substitution | Bromine reacts with alkenes by free-radical addition | Alkenes are formed from alkanes by cracking |
A | ✓ | ✓ | ✓ |
B | ✓ | ✓ | ⨯ |
C | ⨯ | ✓ | ⨯ |
D | ⨯ | ⨯ | ✓ |
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Which of the following compounds will give a positive unsaturation test result with bromine water?
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Which species will not undergo electrophilic addition with an alkene?
HBr
NaOH
Br2
H2SO4
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Which pair of chemicals will give a major and minor product when they undergo electrophilic addition?
Ethene + hydrogen bromide
Propene + bromine
But-1-ene + hydrogen bromide
But-1-ene + bromine
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Which is the most stable carbocation intermediate?
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Polyvinyl chloride, PVC, is a common polymer with many everyday uses.
What is the correct IUPAC name for PVC?
Poly(chloroethane)
Poly(ethane chloride)
Poly(chloroethene)
Poly(ethene chloride)
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Which monomer can form the following addition polymer?
Propene
But-1-ene
But-2-ene
Pent-1-ene
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Consider the reaction between but-1-ene and hydrogen bromide to form the minor product.
Which carbocation is formed in the electrophilic addition mechanism of this reaction?
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Which of the following statements correctly describes ‘electrophilic addition’?
the organic molecule acts as an electrophile and becomes less saturated
the organic molecule acts as an electrophile and becomes more saturated
the organic molecule acts as a nucleophile and becomes less saturated
the organic molecule acts as a nucleophile and becomes more saturated
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Poly(ethenol) is a polymer used to make dissolvable plastic bags. It can be made by the addition polymerisation of ethenol.
Which structure contains a section of the polymer poly(ethenol), showing two repeating units?
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Plasticisers, resins and many other chemicals can be made synthetically by polymerisation of a variety of monomers including but-2-en-1-ol, CH3CH=CHCH2OH.
Which structure is the repeating unit in poly(but-2-en-1-ol)?
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Polyvinyl chloride, PVC, can be used to make pipes, window frames and electrical insulation.
Plasticisers can be added to change the properties of PVC.
Which statement about PVC is not correct?
the repeat unit of PVC is –(CHCl CH2 )–
the empirical formula of PVC is the same as the empirical formula of its monomer
PVC molecules are unsaturated
combustion of PVC waste produces an acidic gas
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Poly(tetrafluoroethene), PTFE, is produced through the polymerisation of tetrafluoroethene.
How does the carbon-carbon bond in tetrafluoroethene compare with that in PTFE?
shorter and weaker
shorter and stronger
longer and weaker
longer and stronger
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Cling film is made through the polymerisation of 1,1-dichloroethene.
The polymer formed is dense with a high melting point and does not allow gases to pass through which makes it ideal for preserving food.
Which sequence appears in a short length of the polymer chain?
[ CHClCHClCHClCHClCHClCHCl ]
[ CCl2CCl2CCl2CCl2CCl2CCl2 ]
[ CH2CCl2CHClCHClCH2CCl2 ]
[ CH2CCl2CH2CCl2CH2CCl2 ]
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A molecule of a polymer contained the sequence shown.
Which monomer could produce this polymer by addition polymerisation?
CH3CCl =CHCl
CH2=CHCl
CHCl =CHCl
CH3CCl =CH2
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Isomers X and Y both react with HBr.
A mixture of X and Y is reacted with HBr.
Which three structures represent three different possible products of this reaction?
A | (CH3)2CHCBr3 | (CH3)2CBrCHBr2 | CH3CHBrCHBrCH3 |
B | (CH3)2CHCBr3 | (CH3)2CBrCHBr2 | CH3CBr2CHBrCH3 |
C | (CH3)2CBrCBr3 | (CH3)2CHCBr3 | CH3CBr2CHBrCH3 |
D | (CH3)2CBrCHBr2 | CHBr2CBr(CH3)CH3 | CH3CHBrCBr2CH3 |
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Limonene is an oil formed in the peel of citrus fruits.
Which product is formed when an excess of bromine, Br2 (l), reacts with limonene at room temperature in the dark?
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Which compound is produced in the reaction between hex-2-ene and steam?
(CH3)2CHCH2CH2CH2OH
CH3CH2CH2CH2CH(OH)CH3
CH3CH2CH(OH)CH2CH3
CH3CH2CH2CH2CH2CH2OH
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Which compound has an Mr of 84 g mol-1 and will react with HBr to give a product with an Mr of 164.9 g mol-1?
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Which description of 2-methylpropene is correct?
2-methylpropene is a saturated alkene that undergoes electrophilic addition reactions
2-methylpropene is an asymmetrical hydrocarbon that forms a mixture of products in reactions with bromine
2-methylpropene will react with hydrogen bromide to form a tertiary halogenoalkane as the major product
2-methylpropene contains a centre of high electron density which causes a temporary induced dipole in sulfuric acid
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Propadiene can undergo electrophilic addition with excess hydrogen bromide.
Which of the following is not a possible product of the reaction?
1,2-dibromopropane
1,3-dibromopropane
1,1-dibromopropane
2,2-dibromopropane
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When 2-methylbuta-1,3-diene undergoes electrophilic addition with hydrogen bromide, which of the following carbocations are possible intermediates?
| Primary | Secondary | Tertiary |
A | ✓ | X | ✓ |
B | X | ✓ | ✓ |
C | ✓ | ✓ | X |
D | ✓ | ✓ | ✓ |
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Sulfuric acid reacts with 2,3-dimethylpent-2-ene via an electrophilic addition mechanism.
Which is the correct pair of carbocation intermediate and product name of the major product?
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An alkene, X, undergoes electrophilic addition with hydrogen bromide to form a halogenoalkane, Y, as the minor product.
The halogenoalkane, Y, can react with sodium cyanide to form pentanenitrile.
What is the correct identity of the alkene, X?
Methylpropene
But-1-ene
But-2-ene
Pent-1-ene
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Most polymers tend to melt gradually over a range of temperatures.
Which is the correct explanation for this?
The variable chain length of polymers leads to variation in the van der Waals forces
Thermal energy is gradually transferred to kinetic energy which breaks the polymer chain structure
Branching in the polymers reduces the induced dipoles between molecules
Thermal energy used for the state change is lost to the surroundings through gaps in the melting polymer’s structure
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Which structure, containing three repeating units, correctly shows the addition polymer formed by E-but-2-ene?
| Polymer 1 | Polymer 2 | Polymer 3 |
A | ✓ | ✓ | ✓ |
B | ✓ | X | ✓ |
C | X | ✓ | X |
D | X | X | ✓ |
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This structure shows a section of a polymer chain formed by the random addition polymerisation of three different monomers.
Which monomers could produce this polymer?
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An alkene, X, with a primary alcohol group contains 62.1% carbon and 10.3% hydrogen.
Which is the correct structure, containing three repeating units, for the addition polymer formed by only one isomer of the alkene, X?
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