Alkenes Flashcards
1
Q
what is the general formula for an alkene
A
CnH₂n
2
Q
what is the alkene functional group
A
carbon-carbon double bond
C=C
3
Q
what are the 3 reactions alkenes undergo
A
-bromination
-hydrogenation
- steam
these are all examples of addition polymerisation
4
Q
describe bromination of ethene
A
-bromine reacts with an alkene to produce a alkane
-C₂H₄ + Br₂ → C₂H₄Br₂
ethene + bromine → 1,2-dibromoethane
5
Q
describe hydrogenation of ethene
A
-an ethene will undergo an addition reaction with hydrogen to form alkanes
C₂H₄ + H₂ → C₂H₆
-a nickel catalyst will be used
6
Q
describe hydration to ethene
A
- ethene will undergo an addition reaction with steam to form an alcohol
- C₂H₄ + H₂O → C₂H₅OH
- 330℃ is used
- 60-70atm
- phosphoric acid catalyst
- this reaction is reversible
7
Q
properties of alkenes
A
- they are unsaturated
- they have carbon-carbon double bonds
- they are more reactive than alkanes because their double bonds can break to add more atoms
8
Q
a test for unsaturation
A
bromine is used to test for unsaturation
if colour changes from orangish-brown to colourless a C=C (carbon-carbon double bond) is present
