IGCSEChemistry: Double ScienceEdexcelExam Questions4. Organic ChemistryCrude Oil

Crude Oil (Edexcel IGCSE Chemistry: Double Science)

Exam Questions

2 hours16 questions
Easy
Medium
Hard
1a1 mark

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)

How did you do?

1b4 marks
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?

  ☐ A electrostatic attraction between oppositely charged ions
  ☐ B

electrostatic attraction between the nuclei of two atoms and a pair of electrons shared between them
  ☐ C electrostatic attraction between positively charged particles and delocalised electrons
  ☐ D electrostatic attraction between atoms

(1)

ii)
The boxes give some uses of fractions and some names of fractions.
 
Draw one straight line from each use to its correct fraction.
1cr-q3

(3)

How did you do?

1c3 marks
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)

How did you do?

1d5 marks
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.
C13H28 → C8H18 + ............................... + ...............................
(2)

How did you do?

Did this page help you?

2a4 marks

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

screen-shot-2022-10-20-at-11-06-11

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

How did you do?

2b4 marks
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)

How did you do?

2c2 marks
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 + ..................................................

How did you do?

Did this page help you?

3a3 marks

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

How did you do?

3b1 mark
b)
Bitumen is collected at the bottom of the column.

Give one use of bitumen.

(1)

How did you do?

3c
Sme Calculator2 marks
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 = ..............................................................

How did you do?

3d2 marks
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 .............................................................................................


How did you do?

3e2 marks
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 + ..................... + .....................

How did you do?

Did this page help you?

1a6 marks

This question is about hydrocarbons.

a)
The table shows the formulae of some hydrocarbons.
screen-shot-2022-10-10-at-16-28-37
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]

iv)
How many of the hydrocarbons are members of the homologous series of alkanes?
[1]

How did you do?

1b3 marks
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] 
ii)
State why this gas is poisonous to humans.
[1] 

How did you do?

1c4 marks
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]

How did you do?

Did this page help you?

21 mark

Incomplete combustion occurs when there is insufficient oxygen for a reaction.

Which are the two main substances formed during incomplete combustion, aside from water?

(1)

  ☐ A Particulates and carbon monoxide 
  ☐ B Soot and sulfur dioxide 
  ☐ C Carbon dioxide and carbon monoxide 
  ☐ D Oxides of nitrogen and sulfur dioxide 

How did you do?

Did this page help you?

3a5 marks

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

screen-shot-2022-10-10-at-20-53-15

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] 

How did you do?

3b3 marks
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] 

How did you do?

3c1 mark
c)
Which of these formulae is that of an alkane?

  ☐ A C7H12
  ☐ B C9H18
  ☐ C C11H24
  ☐ D C13H30

[1] 

How did you do?

3d1 mark
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.

C12H26 → 2C2H4 + .....................................
[1] 

How did you do?

3e5 marks
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]

How did you do?

3f
Sme Calculator4 marks
f)
Alkenes can be distinguished from alkanes using bromine water.

i)
What colour change occurs in the reaction between propene and bromine water?

  ☐ A colourless to orange
  ☐ B colourless to green
  ☐ C green to colourless
  ☐ D orange to colourless

[1] 

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] 

How did you do?

Did this page help you?

41 mark

Cars running on fossil fuels contribute a high amount of pollutants into the atmosphere, one of which is carbon dioxide. 

Which other gas is produced by the internal combustion engine in a car?

(1)

  ☐ A Ammonia
  ☐ B Argon
  ☐ C Oxides of nitrogen
  ☐ D Nitrogen

How did you do?

Did this page help you?

5a2 marks

Propane is a hydrocarbon with the formula C3H8

a)
State why propane is a hydrocarbon.

(2)

How did you do?

5b2 marks

b)

i)
Name the poisonous gas that forms when propane is burned in a limited supply of air.

(1)

ii)
State why this gas is poisonous to humans.

(1)

How did you do?

5c2 marks
c)
The diagram represents a molecule of propane.

2021-ja1c-q9c

Describe the forces of attraction between the atoms in a molecule of propane.

(2)

How did you do?

5d3 marks
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)

How did you do?

5e3 marks
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)

How did you do?

Did this page help you?

61 mark

The diagram shows some processes involved in the oil industry. 

4-2-q3-edexcel-igcse-chemistry

Which process represents cracking?

(1)

  ☐ A  
  ☐ B  
  ☐ C  
  ☐ D  

How did you do?

Did this page help you?

7a2 marks

This question is about hydrocarbons.

a)
State the meaning of the term hydrocarbon.

(2)

How did you do?

7b7 marks
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)

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

2019-ju1cr-q4b

Draw the displayed formulae of the other two isomers.

(2)

How did you do?

7c4 marks
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)

How did you do?

Did this page help you?

8a1 mark

Crude oil is a mixture of hydrocarbons.

a)
Name the process used to separate crude oil into fractions.
(1)

How did you do?

8b1 mark
b)
Give one use of the kerosene fraction.
(1)

How did you do?

8c
Sme Calculator2 marks
c)
One of the hydrocarbons in the refinery gas fraction is an alkane with the structural formula CH3CH2CH2CH3.

i)
Give the name of this alkane.
(1)

ii)
Calculate the relative molecular mass (Mr) of this alkane.
(1)

How did you do?

8d2 marks
d)
One of the alkanes in the gasoline fraction has the displayed formula

alkanes

i)
Determine the molecular formula of this alkane.
(1)

 
ii)
Give the general formula for the alkanes.
(1)

How did you do?

8e2 marks
e)
Catalytic cracking is used to convert long‐chain alkanes into shorter‐chain alkanes.

i)
Name the catalyst used in catalytic cracking.
(1)

ii)
Explain why it is necessary to convert long‐chain alkanes into shorter‐chain alkanes.
(1)

How did you do?

8f2 marks
f)
Catalytic cracking also produces alkenes.

C11H24 can undergo cracking to give pentane (C5H12) and two different alkenes.

Complete the equation for this cracking reaction.

(2)

C11H24 → C5H12 + ............................+............................

How did you do?

Did this page help you?

91 mark

Fractional distillation is the process by which crude oil is separated into simpler, more useful fractions.

Which of the following statements about the process of fractional distillation is correct?

(1)

  ☐ A The fractionating column is cooler at the bottom than at the top
  ☐ B The fractions collected at the top of the fractionating column have a high boiling point
  ☐ C The molecules in each fraction have a similar boiling point and carbon chain length
  ☐ D The fractions collected at the bottom of the fractionating column have a low viscosity

How did you do?

Did this page help you?

10a6 marks

Crude oil is an important source of organic compounds.

a)
The diagram shows crude oil being separated into different fractions.

2019-ju2cr-q3a

i)
Name the process used to separate crude oil into different fractions.

(1)

ii)
State what happens to the crude oil at X.

(1)

iii)
Describe the differences between fraction B and fraction E.

In your answer, refer to

  • size of the molecules
  • boiling point
  • colour
  • viscosity

(4)

How did you do?

10b2 marks
b)
Crude oil often contains sulfur as an impurity.

Explain why this is a problem when using crude oil fractions as fuels.

(2)

How did you do?

Did this page help you?

111 mark

Kerosene, bitumen and diesel oil are fractions obtained through the fractional distillation of crude oil.

Which of the following shows the correct use of each fraction?

(1)

      kerosene bitumen fuel oil
  ☐ A fuel for aircraft surfacing roads in power stations
  ☐ B fuel for trains in power stations fuel for aircraft
  ☐ C in domestic heating surfacing roads in power stations
  ☐ D fuel for aircraft in domestic cooking in domestic cooking

How did you do?

Did this page help you?

12a4 marks
a)
The diagram shows a fractionating column used to separate crude oil into fractions.
 

fractional-distillation

 

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)

How did you do?

12b4 marks
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 + ................................ + ....................................

How did you do?

Did this page help you?

1a4 marks

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.

2021-ja2c-q7a

Describe how crude oil is separated into fractions in the fractionating column.

(4)

How did you do?

1b2 marks
b)
Octane can also be produced by the process of cracking.

Give the conditions for cracking.

(2)

How did you do?

Did this page help you?