Exam code: 5070
Large alkane molecules obtained from petroleum are cracked.
Which pair of substances could both be products of a cracking reaction?
ethane and water
ethene and hydrogen
carbon dioxide and hydrogen
ethanol and ethene
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Oil refineries crack large alkane molecules.
Why is this done?
Smaller alkanes and alkenes are more useful than large alkanes.
Large alkanes are in greater demand than smaller alkanes.
Cracking converts alkenes into alkanes.
Cracking removes sulfur from petroleum.
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Vegetable oils contain carbon–carbon double bonds.
They are hardened to make margarine by reacting them with hydrogen.
Which catalyst is used in this reaction?
iron
nickel
aluminium oxide
vanadium(V) oxide
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But-2-ene, C4H8, reacts with bromine in an addition reaction.
What is the molecular formula of the product?
C4H8Br2
C4H8Br
C4H10Br2
C4H7Br
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Cracking a large alkane molecule requires a high temperature.
Which other condition is required?
ultraviolet light
a high pressure of hydrogen
steam and an acid catalyst
a catalyst
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A student carried out a cracking reaction on hydrocarbon, P, and obtained two products; Q and R.
The student then made the following notes:
Q is unsaturated.
R will decolourise bromine water.
A molecule of P has 7 carbon atoms.
Which of the statements are correct?
1 & 3
1 & 2
2 & 3
1, 2 & 3
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Compound X is shown in the dot-and-cross diagram.
Which statement about compound X is correct?
It is a saturated hydrocarbon.
It is an isomer of butene.
It will decolourise bromine water.
Its name is propane.
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Which row correctly describes alkenes?
| saturated or unsaturated | result when shaken with aqueous bromine |
A | saturated | no change |
B | saturated | the aqueous bromine is decolourised |
C | unsaturated | no change |
D | unsaturated | the aqueous bromine is decolourised |
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Tetradecane, C14H30, is cracked.
The products are two molecules of one alkene, X, and one molecule of octane, C8H18.
What is the molecular formula of X?
C2H4
C3H8
C3H6
C6H12
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Compound Q decolourises aqueous bromine.
One molecule of Q contains five carbon atoms.
Which compound is Q?
C5H12
C5H10
C5H12O
C4H8
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The diagram shows a sequence of reactions.
Which row correctly names the processes P, Q and R?
| P | Q | R |
A | distillation | fermentation | respiration |
B | distillation | hydration | combustion |
C | cracking | fermentation | respiration |
D | cracking | hydration | combustion |
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Hydrocarbons separated by fractional distillation of petroleum can be cracked to make useful shorter chain products.
Which substance is not a product of the cracking of propane, Mr 44?
C4H8
C2H4
C3H6
H2
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The apparatus below was used to test gas Y
The bromine solution quickly went colourless.
What is the correct structure of gas Y?
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The structural formula of compound Z is shown.
CH2=CH–CH=CH2
One molecule of Z reacts completely with aqueous bromine.
How many molecules of bromine react with one molecule of Z?
1
2
3
4
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Propene reacts with bromine.
What type of reaction is this?
addition
halogenation
hydrogenation
polymerisation
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