Name: _______________________________________________
Unit 5 Chemistry past paper
questions
Date:
Time:
Total marks available:
Total marks achieved: ______
,Questions
Q1.
Bromoalkanes are industrially important as solvents for glues and for degreasing surfaces.
They do not occur naturally and are produced from the reaction of hydrocarbons with bromine or
hydrogen bromide.
Propene reacts with hydrogen bromide to produce two possible bromoalkanes.
Figure 4
(i) Draw the displayed structural formula of bromoalkane Y in the box in Figure 4.
(1)
(ii) Identify the reason that propene is able to form two bromoalkanes.
(1)
A It has a symmetrical structure.
B It has an asymmetrical structure.
C It has both cis and trans isomers.
D It has hybridised carbon atoms.
(iii) Identify the name of bromoalkane X in Figure 4.
(1)
A 1-bromopropane
B 1-bromopropene
C 3-bromopropane
D 3-bromopropene
(iv) Propene reacts with hydrogen bromide by an electrophilic addition mechanism.
During the reaction mechanism, a carbocation is formed.
, The two possible carbocations that can form are shown below.
Figure 5
Compare the stability of carbocation A with carbocation B.
(4)
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(Total for question = 7 marks)
Q2.
Pentane is an alkane that has the molecular formula C5H12.
Pentane burns in oxygen.
The process is exothermic.
(i) Name the type of reaction taking place when pentane burns in oxygen.
(1)
.............................................................................................................................................
(ii) Explain how exothermic processes affect their surroundings.
(2)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(iii) The enthalpy change (ΔH) for this reaction is –3509 kJ when one mole of pentane burns in oxygen.
Unit 5 Chemistry past paper
questions
Date:
Time:
Total marks available:
Total marks achieved: ______
,Questions
Q1.
Bromoalkanes are industrially important as solvents for glues and for degreasing surfaces.
They do not occur naturally and are produced from the reaction of hydrocarbons with bromine or
hydrogen bromide.
Propene reacts with hydrogen bromide to produce two possible bromoalkanes.
Figure 4
(i) Draw the displayed structural formula of bromoalkane Y in the box in Figure 4.
(1)
(ii) Identify the reason that propene is able to form two bromoalkanes.
(1)
A It has a symmetrical structure.
B It has an asymmetrical structure.
C It has both cis and trans isomers.
D It has hybridised carbon atoms.
(iii) Identify the name of bromoalkane X in Figure 4.
(1)
A 1-bromopropane
B 1-bromopropene
C 3-bromopropane
D 3-bromopropene
(iv) Propene reacts with hydrogen bromide by an electrophilic addition mechanism.
During the reaction mechanism, a carbocation is formed.
, The two possible carbocations that can form are shown below.
Figure 5
Compare the stability of carbocation A with carbocation B.
(4)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(Total for question = 7 marks)
Q2.
Pentane is an alkane that has the molecular formula C5H12.
Pentane burns in oxygen.
The process is exothermic.
(i) Name the type of reaction taking place when pentane burns in oxygen.
(1)
.............................................................................................................................................
(ii) Explain how exothermic processes affect their surroundings.
(2)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(iii) The enthalpy change (ΔH) for this reaction is –3509 kJ when one mole of pentane burns in oxygen.
