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Edexcel International A Level Chemistry

Reactions of Alkenes

Alkenes react because the C=C double bond contains an exposed pi bond with high electron density. These pages separate the key alkene reactions so that students can revise the reagent, conditions, observations and products for each pathway.

Exam Unit
Unit 1
WCH11/01 – IAS
Specification Points
5.4 – 5.6
3 points covered
Sub-topics
6 lessons
Revision notes available
Exam Board
Edexcel IAL
Pearson International

Revision Notes

Reactions of Alkenes
Halogens
dihalogenoalkanes from Br₂ and Cl₂
1

Halogens

Revise addition of halogens to alkenes and how dihalogenoalkanes form across the carbon-carbon double bond.

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Reactions of Alkenes
Hydrogen Halide
hydrogen halides add across the C=C bond
2

Hydrogen Halide

Learn how hydrogen halides add to alkenes to form halogenoalkanes, including the importance of the C=C bond.

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Reactions of Alkenes
Bromine Water
bromine water test for C=C
3

Bromine Water

Revise the chemical test for alkenes, including the colour change when bromine water reacts with a C=C bond.

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Reactions of Alkenes
Hydrogen
hydrogenation with a nickel catalyst
4

Hydrogen

Learn how hydrogenation converts alkenes into alkanes by adding hydrogen across the double bond.

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Reactions of Alkenes
Steam
steam and an acid catalyst give alcohols
5

Steam

Revise hydration of alkenes and how steam is used to produce alcohols under suitable conditions.

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Reactions of Alkenes
KMnO₄
diols from acidified KMnO₄
6

KMnO₄

Review oxidation of alkenes with potassium manganate(VII), including the key reagent and expected test observations.

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Specification Coverage

Reactions of Alkenes – Edexcel International A Level Chemistry

The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 5.

5.4
be able to describe the reactions of alkenes, limited to:
i
the addition of hydrogen, using a nickel catalyst, to form an alkane
ii
the addition of halogens to produce a di-substituted halogenoalkane
iii
the addition of hydrogen halides to produce mono-substituted halogenoalkanes
iv
the addition of steam, in the presence of an acid catalyst, to produce alcohols
v
oxidation of the double bond by acidified potassium manganate(VII) to produce a diol
5.5
know the qualitative test for a C=C double bond using bromine or bromine water
5.6
be able to describe the mechanism (including diagrams), giving evidence where possible, of:
i
the electrophilic addition of bromine and hydrogen bromide to ethene
ii
the electrophilic addition of hydrogen bromide to propene
Use of the curly arrow notation is expected. The curly arrows should start from either a bond or from a lone pair of electrons. Knowledge of primary, secondary and tertiary carbocation stability is expected.
Specification Coverage

Reactions of Alkenes – Edexcel International A Level Chemistry

The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 5.

5.4
be able to describe the reactions of alkenes, limited to:
i
the addition of hydrogen, using a nickel catalyst, to form an alkane
ii
the addition of halogens to produce a di-substituted halogenoalkane
iii
the addition of hydrogen halides to produce mono-substituted halogenoalkanes
iv
the addition of steam, in the presence of an acid catalyst, to produce alcohols
v
oxidation of the double bond by acidified potassium manganate(VII) to produce a diol
5.5
know the qualitative test for a C=C double bond using bromine or bromine water
5.6
be able to describe the mechanism (including diagrams), giving evidence where possible, of:
i
the electrophilic addition of bromine and hydrogen bromide to ethene
ii
the electrophilic addition of hydrogen bromide to propene
Use of the curly arrow notation is expected. Knowledge of primary, secondary and tertiary carbocation stability is expected.