ALKENES
Alkenes are a homologous series of ……………………………………………
What are alkenes?
number of
C atoms
CnH2n
hydrocarbons with the general formula ……………………….
.
displayed formula
molecular formula
ethene
propene
butene
pentene
REACTIONS OF ALKENES
 Alkenes are very reactive due to presence of the C=C double bond which undergoes addition reactions
 In addition reactions, the C=C double bond becomes a C-C single bond and other atoms join onto the two C
atoms
 Alkenes do also burn, but they are rarely burned as they are (a) too valuable for making polymers and (b) tend
to undergo incomplete combustion with smoky flames
1) halogens (Cl2, Br2, I2)
1
2
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11-July-2017
Chemsheets GCSE 1232
3
4
5
 The fact that alkenes react with and decolourise bromine water is used as a test for C=C double bonds
2) hydrogen (H2) (at 150C with nickel catalyst – to make ALKANES)
1
2
3
3) steam (H2O) (at high temperature with concentrated phosphoric acid catalyst – to make ALCOHOLS)
1
2
© www.CHEMSHEETS.co.uk
11-July-2017
Chemsheets GCSE 1232