Questions

Q12.

Crude oil is a mixture of organic compounds.

Most of these compounds are members of the same homologous series.

(a) State the name of this homologous series.

(1)
.............................................................................................................................................

(b) An industrial process is used to separate crude oil into fractions.

(i) The process depends on a difference in a property of the fractions.
What is this property?
(1)
A boiling point
B density
C melting point
D solubility

(ii) The boxes give some uses of fractions and some names of fractions.
Draw one straight line from each use to its correct fraction.
(3)

(c) Fuels obtained from the fractions may contain impurities.

Explain how the combustion of a common impurity in fuels may cause an environmental problem.
(3)
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(d) Some of the fractions contain long-chain molecules which are not very useful.
(i) Give the name of the process used to convert long-chain molecules into more useful shorter-chain
molecules.
(1)
.............................................................................................................................................
(ii) Give the catalyst and temperature used in the industrial process to convert long-chain molecules
into
shorter-chain molecules.
(2)
catalyst ...................................................................................................................................

temperature. ...............................................................................................................................
(iii) When C13H28 is used in this process, three different molecules are formed.
Complete the equation for this reaction.
(2)
C13H28 → C8H18 + ............................... + ...............................

(Total for question = 13 marks)

Q13.

(a) An alkane has the molecular formula C3H8

(i) Give the name of this alkane.
(1)
.............................................................................................................................................
(ii) Draw the displayed formula of this alkane.
(1)

(iii) Give the general formula for the alkanes.

(1)
.............................................................................................................................................

(b) The alkanes C2H6 and C4H10 contain covalent bonds and have simple molecular structures.
(i) State what is meant by the term covalent bond.
(1)
.............................................................................................................................................
 .............................................................................................................................................
(ii) Explain why C4H10 has a higher boiling point than C2H6
(3)
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(c) The organic compound tetrafluoroethene (C2F4) can be polymerised to form poly(tetrafluoroethene).
(i) Complete the equation for this polymerisation reaction.
(2)

(ii) Poly(tetrafluoroethene) is used as a coating on non-stick frying pans.

The C—F covalent bonds in poly(tetrafluoroethene) are very strong.
Suggest a reason why poly(tetrafluoroethene) is suitable as a coating on non-stick frying pans.
(1)
.............................................................................................................................................

.............................................................................................................................................

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(Total for question = 10 marks)

Q14.

This question is about alkenes and alkanes.

(a) Complete the table by giving the missing information about the alkene with the molecular formula
C3H6
(4)
(b) Alkenes are unsaturated compounds.
(i) State what is meant by the term unsaturated.
(1)
.............................................................................................................................................

.............................................................................................................................................
(ii) Describe a test to show that a compound is unsaturated.
(2)
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(c) When the alkane methane reacts with chlorine, the products are chloromethane (CH3Cl) and
hydrogen chloride gas.
(i) Give a chemical equation for this reaction.
(1)
.............................................................................................................................................
(ii) What is the name of this type of reaction?
(1)
A addition
B decomposition
C neutralisation
D substitution

(iii) State the condition needed for this reaction to occur.

(1)
.............................................................................................................................................

(d) When ethane reacts with chlorine, one of the products of the reaction has the formula C2H4Cl2
There are two isomers with this formula.
(i) State what is meant by the term isomers.
(2)
.............................................................................................................................................

.............................................................................................................................................
 .............................................................................................................................................

.............................................................................................................................................
(ii) Draw the displayed formulae of the two isomers with the formula C2H4Cl2
(2)

(Total for question = 14 marks)

Q15.

This question is about alkenes and polymers.

(a) (i) Ethene (C2H4) can be represented by different types of formula.

Complete the table by giving the missing information.
(2)

(ii) Ethene is a member of the homologous series of alkenes.

All members of the same homologous series have the same general formula.
Give two other characteristics of a homologous series.
(2)
1 ..........................................................................................................................................

.............................................................................................................................................

2 ..........................................................................................................................................

.............................................................................................................................................

(b) Ethene is used to make poly(ethene).

(i) State the type of polymerisation used to form poly(ethene).
(1)
.............................................................................................................................................
(ii) Complete the equation for the polymerisation of ethene.
(2)

(iii) Poly(ethene) is used to make plastic bags.

Corn starch from plants can also be used to make polymers for plastic bags.
The table gives some information about poly(ethene) and polymers made from corn starch.

Use the information in the table and your knowledge to discuss the advantages and disadvantages
of using poly(ethene) to make plastic bags.
(5)
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(c) The diagram shows the repeat unit of another polymer.

Draw the displayed formula of the monomer used to make this polymer.
(1)

(Total for question = 13 marks)

Q24.

Crude oil is an important source of organic compounds.

(a) The diagram shows how crude oil can be separated into fractions by fractional distillation.

(i) State what happens to the crude oil when it is in X.

(1)
.............................................................................................................................................

.............................................................................................................................................
(ii) Give the name of fraction E.
(1)
.............................................................................................................................................
(iii) Give a use for fraction A.
(1)
 .............................................................................................................................................

(b) One of the compounds in fraction D is tridecane (C13H28) which can be cracked to form shorter-chain
hydrocarbons.
(i) State the catalyst and temperature used in this cracking reaction.
(2)
catalyst
.............................................................................................................................................
temperature
.............................................................................................................................................

(c) Sulfur is an impurity in crude oil.

Explain why this is a problem for the environment.
(3)
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Q26.
This question is about fractions obtained from crude oil.
(a) The diagram shows a fractional distillation column and two of the fractions obtained from crude oil.

Describe how the colour, boiling point and viscosity of fraction X differs from the kerosene fraction.
(3)
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(b) Octane (C8H18) is part of the gasoline fraction.

In a limited supply of air, octane undergoes incomplete combustion.
(i) Complete the chemical equation for the incomplete combustion of octane.
(2)
C8H18 + ................................O2 → 5CO + ................................CO2 + ................................H2O
(ii) Give a reason why carbon monoxide (CO) gas is poisonous.
(1)
.............................................................................................................................................

.............................................................................................................................................
(iii) Explain how the combustion of a common impurity in gasoline may cause an environmental
problem.
(3)
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(c) Ethene is obtained from one of the fractions in crude oil.

Ethene is used to make the polymer poly(ethene).
(i) Complete the equation for the conversion of ethene to poly(ethene).
(2)

(ii) Explain why poly(ethene) is difficult to dispose of in landfill sites.

(2)
.............................................................................................................................................

.............................................................................................................................................

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(Total for question = 13 marks)

Q27.

Crude oil is a mixture of hydrocarbons.

(a) This passage is about the industrial separation of crude oil.

Complete the passage by adding the missing words.
(3)
Crude oil is ............................................................................................. to form vapour.
The vapour is passed through a ............................................................................................. column.
The refinery gases are collected at the top of the column because they have low
................................................ ...............................................
(b) Bitumen is collected at the bottom of the column.
Give one use of bitumen.
(1)
.............................................................................................................................................

(c) One of the hydrocarbons in crude oil is an alkane with this structural formula.

CH3CH2CH2CH2CH3
(i) Give the name of this alkane.
(1)
.............................................................................................................................................
(ii) Calculate the relative molecular mass (Mr) of this alkane.
(1)

Mr = ...........................................................

(d) Catalytic cracking is used to convert long-chain alkanes into shorter-chain alkanes.
Give the name of the catalyst and the temperature used in catalytic cracking.
(2)
catalyst .............................................................................................................................................

temperature .............................................................................................................................................

(e) Catalytic cracking also produces alkenes.

Decane (C10H22) can undergo cracking to give C4H10 and two different alkenes.
Complete the equation for this cracking process.
(2)
C10H22 → C4H10 + .............................................................. + ..............................................................
Q33.

This question is about ethane and ethene.

(a) Ethane can be obtained from crude oil.

Describe the industrial process used to separate crude oil into fractions.
(4)
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(b) The equation for the reaction between ethene gas and hydrogen gas is

C2H4 + H2 → C2H6
The rate of this reaction can be increased by increasing the pressure.
(i) Explain why increasing the pressure increases the rate of this reaction.
(2)
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(ii) The rate of this reaction can also be increased by using a catalyst.
Explain how using a catalyst increases the rate of a reaction.
(2)
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(iii) Give one other way that the rate of reaction between ethene gas and hydrogen gas can be
increased.
 (1)
.............................................................................................................................................

.............................................................................................................................................
(iv) The reaction between ethene and hydrogen is exothermic.
Complete the reaction profile diagram, including labels for the activation energy and the enthalpy
change, ΔH.
(3)

(c) The reaction between ethene and hydrogen can be represented using displayed formulae.

Use the bond energies in the table to calculate the enthalpy change, ΔH, in kJ/mol for this reaction.
(3)

ΔH ........................................................... kJ/mol

(Total for question = 15 marks)

Q38.

(a) Two of the fractions obtained from crude oil are gasoline and bitumen.
(i) This is the displayed formula for one of the alkanes in the gasoline fraction.

Determine the molecular formula of this alkane.

(1)
.............................................................................................................................................
(ii) Give a use of bitumen.
(1)
.............................................................................................................................................
(iii) Describe the differences between the gasoline and bitumen fractions, in terms of colour, boiling
point
and viscosity.
(3)
colour ...................................................................................................................................

.............................................................................................................................................

boiling point ...........................................................................................................................

.............................................................................................................................................

viscosity ................................................................................................................................

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(b) Methane is an alkane used as a fuel.

When methane burns in a plentiful supply of air, carbon dioxide and water vapour form.
The equation for the reaction is
CH4 + 2O2 → CO2 + 2H2O
The diagram shows how water can be collected when methane burns in the air.

(i) Water freezes at 0 °C and boils at 100 °C.

Carbon dioxide sublimes at −78 °C.
Explain why water collects in the U-tube, but carbon dioxide does not.
(4)
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(ii) Describe how anhydrous copper(II) sulfate can be used to show that the U-tube contains water.
(2)
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(Total for question = 11 marks)

Q39.

The diagram shows the industrial equipment used to separate crude oil into fractions.

(a) (i) Give the name of the industrial equipment.

(1)
.............................................................................................................................................
(ii) Give one use of the fuel oil fraction.
(1)
.............................................................................................................................................
(iii) Give the names of fraction A and fraction F.
 (2)
fraction A .............................................................................................................................................

fraction F .............................................................................................................................................

(b) One compound in the gasoline fraction is the alkane octane (C8H18) and one compound in the
kerosene fraction is the
alkane dodecane (C12H26)
These two alkanes are covalently bonded and have simple molecular structures.
(i) Give the general formula for the alkanes.
(1)
.............................................................................................................................................
(ii) Explain, in terms of their structures, why C12H26 has a higher boiling point than C8H18
(3)
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(c) Catalytic cracking can be used to convert the alkane C12H26 into more useful products.
(i) Give the name of the catalyst used for catalytic cracking.
(1)
.............................................................................................................................................
(ii) Complete the equation for this cracking reaction.
(1)
C12H26 → C9H20 + ..................................................

(Total for question = 10 marks)

Q40.

(a) The diagram shows a fractionating column used to separate crude oil into fractions.
 (i) Give a use for bitumen and a use for gasoline.
(2)
use for bitumen...........................................................................................................................

use for gasoline..........................................................................................................................

(ii) Explain why bitumen is collected at the bottom of the fractionating column and gasoline is collected
near the top
of the fractionating column.
(2)
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(b) There is a low demand for some of the fractions obtained from crude oil.
Cracking can be used to convert these fractions into more useful substances.
(i) State the conditions needed for cracking.
(2)
.............................................................................................................................................

.............................................................................................................................................
(ii) Dodecane (C12H26) can be cracked to produce an alkane and two alkenes.
Complete the equation by giving the formulae of the two alkenes.
(2)
C12H26 → C7H16 + .............................................................. + ..............................................................

(Total for question = 8 marks)

Q41.

Fractional distillation is used to separate crude oil into fractions.

The diagram shows a fractionating column and the fractions obtained from crude oil.
(a) (i) Describe how crude oil is separated into fractions in the fractionating column.
(4)
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(ii) Give a use for kerosene and a use for bitumen.
(2)
kerosene
.............................................................................................................................................

.............................................................................................................................................
bitumen
.............................................................................................................................................

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(b) Some fractions obtained from crude oil are cracked to form alkenes.
(i) Describe what is meant by cracking.
(2)
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(ii) Ethene is obtained by cracking.
This is the displayed formula of ethene.

Explain why ethene is described as an unsaturated hydrocarbon.

(3)
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(iii) Describe a test to show that ethene is unsaturated.
(2)
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(Total for question = 13 marks)

Q43.

This question is about gases in the air.

The pie chart represents the percentages of gases in dry, unpolluted air.

Gases with percentages of less than 1% in air are called trace gases.
(a) (i) Which of these is gas Z?
(1)
A hydrogen
B methane
C neon
D nitrogen

(ii) Which of these is the approximate percentage of oxygen in dry, unpolluted air?
(1)
A 0.04%
B 0.9%
C 21%
D 35%

(b) One of the trace gases is carbon dioxide.

(i) Identify two reactions that produce carbon dioxide by placing a tick (✓) in two boxes.
(2)

(ii) Name an environmental problem that is caused by the percentage of carbon dioxide increasing in
the atmosphere.
(1)
.............................................................................................................................................
(iii) Name the trace gas with the highest percentage in dry, unpolluted air.
(1)
.............................................................................................................................................

(c) Rainwater is acidic because carbon dioxide dissolves in water to form carbonic acid.
Acid rain is more acidic than rainwater because acidic pollutant gases also dissolve in water.
(i) Give the name of the acid that forms when nitrogen dioxide dissolves in water.
(1)
.............................................................................................................................................
(ii) Name another pollutant gas that also forms acid rain.
(1)
.............................................................................................................................................

(Total for question = 8 marks)

Q44.
This question is about gases in the atmosphere.

(a) The box gives the names of some gases in the atmosphere.

Choose gases from the box to answer these questions.

Each gas may be used once, more than once or not at all.
(i) Identify a noble gas.
(1)
.............................................................................................................................................
(ii) Identify a gas that makes up about 78% of the atmosphere.
(1)
.............................................................................................................................................
(iii) Identify a greenhouse gas.
(1)
.............................................................................................................................................
(iv) Identify a gas produced by the thermal decomposition of calcium carbonate.
(1)
.............................................................................................................................................

(b) Sulfur reacts with oxygen to produce sulfur dioxide gas.

(i) Write a chemical equation for this reaction.
(1)
.............................................................................................................................................
(ii) State an environmental problem caused when sulfur dioxide gas dissolves in water in the
atmosphere.
(1)
.............................................................................................................................................

.............................................................................................................................................

(Total for question = 6 marks)

Q45.

This question is about hydrocarbons.

(a) The table shows the formulae of some hydrocarbons.

 (i) Give the letters that represent hydrocarbons with the general formula CnH2n
(1)
.............................................................................................................................................

.............................................................................................................................................
(ii) State why B is the only hydrocarbon shown as a displayed formula.
(1)
.............................................................................................................................................
(iii) Explain which two letters represent isomers.
(3)
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(iv) How many of the hydrocarbons are members of the homologous series of alkanes?
(1)
.............................................................................................................................................

(b) Many hydrocarbons are used as fuels. There are problems associated with this use.
(i) Explain how the combustion of a hydrocarbon can lead to the formation of a poisonous gas.
(2)
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(ii) State why this gas is poisonous to humans.
(1)
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(c) Fuels used in cars often have sulfur compounds removed.

Explain how the combustion of these fuels in car engines still leads to the formation of acid rain.
(4)
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(Total for question = 13 marks)

Q46.

This question is about hydrocarbons.

(a) State the meaning of the term hydrocarbon.

(2)
.............................................................................................................................................

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(b) One homologous series of hydrocarbons is the alkanes.

Pentane (C5H12) is an alkane.
(i) When pentane burns completely in oxygen, carbon dioxide and water are produced.
Give a chemical equation for this combustion reaction.
(2)
.............................................................................................................................................
(ii) Incomplete combustion can occur when the oxygen supply is limited.
Give the names of two products of the incomplete combustion of pentane.
(2)
1 ..........................................................................................................................................

2 ..........................................................................................................................................
(iii) One of the products of incomplete combustion is a poisonous gas.
State why this gas is poisonous to humans.
(1)
.............................................................................................................................................

.............................................................................................................................................
(iv) C5H12 has three isomers.
The displayed formula for one of these isomers is
 Draw the displayed formulae of the other two isomers.
(2)

(c) Another homologous series of hydrocarbons is the alkenes.

Alkenes are unsaturated hydrocarbons.
(i) Give the general formula for the alkenes.
(1)
.............................................................................................................................................
(ii) State the meaning of the term unsaturated.
(1)
.............................................................................................................................................

.............................................................................................................................................
(iii) Describe a test to show that a hydrocarbon is unsaturated.
(2)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................

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(Total for question = 13 marks)

Q47.

The flow chart shows how ethene can be obtained industrially from crude oil.

(a) Step 1 involves the use of a tall column.

Describe how the diesel fraction is obtained from the crude oil in step 1.
(5)
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(b) In step 2, saturated compounds such as dodecane are obtained from the mixture of hydrocarbons in
the diesel fraction.
Explain why dodecane is described as a saturated hydrocarbon.
(3)
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(c) Which of these formulae is that of an alkane?

(1)
A C7H12

B C9H18

C C11H24

D C13H30

(d) In step 3, cracking is used to convert alkanes into alkenes.

Complete the equation to show the reaction in which one molecule of dodecane is converted into two
molecules of ethene and one molecule of another hydrocarbon.
(1)
C12H26 → 2C2H4 + ........................................

(e) Alkanes and alkenes both react with halogens, but in different ways.
The equations for two examples of these different reactions are shown.
equation 1 C2H6 + Cl2 → C2H5Cl + compound X
equation 2 C2H4 + Br2 → C2H4Br2
 (i) State the condition needed for the reaction in equation 1 to occur.
(1)
.............................................................................................................................................
(ii) Deduce the formula of compound X.
(1)
.............................................................................................................................................
(iii) Draw a dot-and-cross diagram to represent a molecule of C2H5Cl
Show only the outer electrons of each atom.
(2)

(iv) Equation 2 shows an example of an addition reaction.

State the type of reaction shown by equation 1.
(1)
.............................................................................................................................................

(f) Alkenes can be distinguished from alkanes using bromine water.

(i) What colour change occurs in the reaction between propene and bromine water?
(1)
A colourless to orange
B colourless to green
C green to colourless
D orange to colourless

(ii) A compound formed in the reaction between propene and bromine water has the percentage
composition by mass
C = 25.9%, H = 5.0%, Br = 57.6% and O = 11.5%
Calculate the empirical formula of this compound.
(3)

empirical formula = ...........................................................

(Total for question = 19 marks)

Q49.

This question is about octane (C8H18) which is produced in the gasoline fraction during fractional
distillation of crude oil.

(a) The diagram shows a fractionating column.

 Describe how crude oil is separated into fractions in the fractionating column.
(4)
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(b) Octane can also be produced by the process of cracking.

Give the conditions for cracking.
(2)
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(c) A car is driven at constant speed for 4.00 km.

The exhaust gases are collected and their volume at room temperature and pressure (rtp) is 5.02 ×
105 cm3.
The exhaust gases include carbon dioxide and oxides of nitrogen.
The carbon dioxide is removed from the exhaust gases. The volume of the remaining gases at rtp is
2.96 × 105 cm3.
(i) Explain how oxides of nitrogen form in a car engine.
(2)
.............................................................................................................................................

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 (ii) Give a reason why oxides of nitrogen should not be released into the atmosphere.
(1)
.............................................................................................................................................

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(iii) Show that the car produces less than 100 g of carbon dioxide per km.
[molar volume of carbon dioxide at rtp = 24 000 cm3]
(5)

(Total for question = 14 marks)

Q50.

This question is about organic compounds.

(a) The diagram shows the displayed formulae of five compounds, U, V, W, X and Y.

(i) Give the letter of the compound that is not a hydrocarbon.

(1)
.............................................................................................................................................
(ii) Give the letter of the compound that is a saturated hydrocarbon with the empirical formula CH2
(1)
.............................................................................................................................................
(iii) Give the letter of the compound that reacts with bromine in the presence of ultraviolet radiation to
form this structure.
(1)

.............................................................................................................................................
(iv) Give the letter of the compound that forms an addition polymer with this repeat unit.
(1)

.............................................................................................................................................
 (v) Give the displayed formula of an alkene that is an isomer of compound X.
(1)

(vi) Compounds U and X are members of the same homologous series.

Members of the same homologous series have the same functional group.
Give two other characteristics of compounds in the same homologous series.
(2)
1 ..........................................................................................................................................

.............................................................................................................................................

2 ..........................................................................................................................................

.............................................................................................................................................

(b) Compound Z contains 38.7% carbon, 9.7% hydrogen and 51.6% oxygen by mass.
(i) Show by calculation that the empirical formula of compound Z is CH3O
(2)

(ii) The relative formula mass (Mr) of compound Z is 62

Deduce the molecular formula of compound Z.
(2)

molecular formula = ...........................................................

(Total for question = 11 marks)

Q52.

The table shows the displayed formulae of some organic compounds.

(a) Give a reason why compound X is not a hydrocarbon.

(1)
.............................................................................................................................................

.............................................................................................................................................

(b) Give the letter of the compound that is a saturated hydrocarbon with the empirical formula CH2
(1)
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(c) Give the letter of the compound that produces nine moles of water when one mole undergoes
complete combustion.
(1)
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(d) Give the structural formula of compound Y.

(1)
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(e) Explain why compounds W and Y are isomers.

(2)
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(f) Compound Z reacts with bromine in the presence of ultraviolet radiation.

(i) Write a chemical equation for this reaction.
(2)
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 (ii) What is the name for this type of reaction?
(1)
A addition
B combustion
C substitution
D thermal decomposition

(g) Describe how the combustion of sulfur-free petrol in a car engine produces gases that can cause acid
rain.
Do not refer to carbon dioxide in your answer.
(3)
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(Total for question = 12 marks)

Q55.

Propane is a hydrocarbon with the formula C3H8

(a) State why propane is a hydrocarbon.

(2)
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(b) (i) Name the poisonous gas that forms when propane is burned in a limited supply of air.
(1)
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(ii) State why this gas is poisonous to humans.
(1)
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(c) The diagram represents a molecule of propane.

 Describe the forces of attraction between the atoms in a molecule of propane.
(2)
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(d) Propane can be produced by cracking.

An equation for cracking is
C13H28 → C3H8 + 2C3H6 + 2C2H4
Explain why cracking is an important process in the oil industry.
(3)
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(e) Propane reacts with bromine in the presence of ultraviolet radiation.

(i) Complete the equation for this reaction.
(2)
C3H8 + Br2 → ........................................................... + ...........................................................
(ii) Give the name of this type of reaction.
(1)
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(Total for question = 12 marks)

Q56.

This question is about propene.

(a) (i) The structural formula of propene is

Complete the dot-and-cross diagram for a molecule of propene.
(2)

(ii) Describe the forces of attraction that hold the atoms together in a molecule of propene.
(2)
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(b) The alkane pentadecane has the formula C15H32

Describe how propene can be produced from pentadecane.
(2)
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(c) Propene is used to make poly(propene).

(i) Complete the equation for the formation of poly(propene).
(2)

(ii) Explain why the disposal of poly(propene) in landfill sites is a problem.

(2)
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(d) Propene can be converted into compound X.

(i) Compound X contains these percentages by mass.

• carbon 60%
• hydrogen 13.3%
• oxygen 26.7%
Compound X has an Mr of 60
Determine the molecular formula of compound X.
(3)

molecular formula = ...........................................................

(ii) Propene and compound X both have simple molecular structures.
Explain why compound X has a higher boiling point than propene.
(2)
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(Total for question = 15 marks)