IGCSEChemistry: Double ScienceEdexcelTopic Questions4. Organic Chemistry4.4 Alkenes

Alkenes (Edexcel IGCSE Chemistry: Double Science)

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1a3 marks

This question is about the unsaturated hydrocarbon, ethene.

The displayed formula of ethene is

ethene-q-image

a) i)
State the meaning of the term hydrocarbon.
 
(2)
 
ii)
Give the reason why ethene is described as unsaturated.
 
(1)

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1b1 mark
b
)
Ethene is bubbled through bromine water until there is no further colour change.
 
Which of these is the appearance of the solution formed?
 
(1)
 
  ☐ A colourless
  ☐ B orange
  ☐ C purple
  ☐ D red

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1a5 marks

The table shows the structures of six organic compounds.

organic-compounds-table

a) i)
Give the letter of a compound not shown as a displayed formula.
 
(1)
 
ii)
Give the letter of a saturated compound with the general formula CnH2n
 
(1)
 
iii)
Name compound E.
 
(1)
 
iv)
Explain why compound A and compound D are isomers.
 
(2)

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1b2 marks
b)
Compound F reacts with bromine in the presence of ultraviolet radiation.
 
i)
Complete the equation for the reaction.
 
(1)
 
   CH4 + Br2 →
 
ii)
Give the name of this type of reaction.
 
(1)

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1c
Sme Calculator5 marks
c) i)
Another compound, G, has this percentage composition by mass.
 
C = 37.8%   H = 6.3%   Cl = 55.9%
 
Show by calculation that the empirical formula of compound G is C2H4Cl
 
(3)
 
ii)
The relative formula mass (Mr) of G is 127
 
Determine the molecular formula of G.
 
(2)
 
molecular formula = ..............................

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1d3 marks
d)
Compound E is used to make an addition polymer.
 
i)
Complete the equation to show part of the polymer formed from two molecules of compound E.
 
(2)
 
polymerisation-of-compound-e
 
ii)
Give one problem caused by the disposal of addition polymers.
 
(1)

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11 mark

Which of the following molecules is an alkene?

(1)

  ☐ A C6H10
  ☐ B C4H10
  ☐ C C5H10
  ☐ D C6H14

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2a4 marks

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)

 Molecular formula C3H6
 Name  
 Empirical formula  
 General formula  
 Displayed formula





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2b3 marks
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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2c3 marks
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)

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2d4 marks
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)
Isomer 1 Isomer 2
 






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31 mark

Bromine water is an orange-brown solution.

When shaken with bromine water, which of the following compounds would cause the solution to decolourise?

(1)

  ☐ A C3H8
  ☐ B C9H20
  ☐ C C6H16
  ☐ D C4H8

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4a
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Ocimene is an organic compound that gives some plants their particular smell.

The molecular formula of ocimene is C10H16

a)
Calculate the relative formula mass (Mr) of ocimene.
 
(1)
 
Mr = ..............................

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4b2 marks
b)
Using ocimene as an example, explain what is meant by the term empirical formula.
 
(2)

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4c3 marks
c)
The displayed formula of ocimene is
 
ocimene
 
Explain why ocimene is described as an unsaturated hydrocarbon.
 
(3)

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4d2 marks
d)
Ocimene is an alkene.
 
i)
Which of these types of reaction occurs between ocimene and bromine?
 
A addition
B polymerisation
C precipitation
D substitution
 
(1)
 
ii)
Many alkenes have the general formula CnH2n
 
Suggest why ocimene does not have this general formula.
 
(1)

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4e2 marks
e)
Ocimene can take part in combustion reactions.
 
Complete the equation for the complete combustion of ocimene.
 
(2)
 
C10H16 + .......... O2 → .............................. + ..............................

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4f3 marks
f)
Two different products can form during the incomplete combustion of ocimene.
 
One product is a solid and the other is a poisonous gas.
 
i)
Identify these two products.
 
(2)
 
ii)
State why the gas produced is poisonous.
 
(1)

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51 mark

The structures of some organic compounds are shown below. 

kiqUd87q_hydrocarbons

Compound R can be converted to compound T by reacting it with bromine. 

What kind of reaction is this?

(1)

  ☐ A Substitution
  ☐ B Displacement
  ☐ C Combustion 
  ☐ D Addition

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61 mark

The displayed formula of alkene Y is shown below:

4-4-q4-edexcel-igcse-chemistry

What is the name of alkene Y?

(1)

  ☐ A Ethene
  ☐ B Propene
  ☐ C Butene
  ☐ D Pentene

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71 mark

Name the product formed from the reaction between ethene and chlorine. 

(1)

  ☐ A Chloroethane
  ☐ B Chloroethene
  ☐ C Dichloroethane
  ☐ D Dichloroethene

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