Topic 6 - Alkenes

Question 1

are alkenes hydrocarbons?

Answer 1

yes - they are hydrocarbons with a double bond between two of the carbon atoms

Question 2

are alkenes saturated?

Answer 2

no - they are unsaturated because they have a double carbon bond

Question 3

what is the general formula for alkenes?

Answer 3

CₙH₂ₙ

Question 4

what is the molecular and structural formula of ethene?

Answer 4

molecular: C₂H₄
structural: CH₂CH₂

Question 5

what is the molecular and structural formula of propene?

Answer 5

molecular: C₃H₆
structural: CH₂CHCH₂

Question 6

what is the molecular formula of butene?

Answer 6

C₄H₈

Question 7

what is the structural formula of But-1-ene?

Answer 7

CH₂CHCH₂CH₃

Question 8

what is the structural formula of But-2-ene?

Answer 8

CH₃CHCHCH₃

Question 9

what is created when a halogen reacts with an alkene?

Answer 9

a haloalkane

Question 10

what is the reaction between an alkene and a halogen called?

Answer 10

an addition reaction - the C=C double bond splits and a halogen atoms is added to each of the carbons

Question 11

how is bromine and alkenes used as a test for carbon-carbon double bonds?

Answer 11

when you shake an alkene with orange bromine water the solution becomes colourless as the alkene and bromine react.
an alkane will not react with bromine water as they don’t have a double bond.