alkenes

Question 1

Which statement is correct about poly(chloroethene)?
A It has the empirical formula CHCl
B It decolourises bromine water.
C Its brittleness is reduced by plasticisers.
D Its polymer chain contains alternate single and double
bonds.

Answer 1

C

Question 2

Which statement about E-1,2-dichloroethene is correct?

A
It has the same boiling point as
Z-1,2-dichloroethene.
B It forms a polymer with the same repeating unit
as Z-1,2-dichloroethene.
C It has the same IR spectrum as Z-1,2-dichloroethene
in the range 400–1500 cm−1
.
D It has a molecular ion peak different from that of
Z-1,2-dichloroethene in its mass spectrum

Answer 2

A

Question 3

Which statement about ethene is correct?
A It has no geometric isomers because there is free rotation
around the C=C bond.
B It reacts with HBr in a nucleophilic addition reaction.
C It burns in excess oxygen to produce carbon dioxide and water.
D The C=C bond is twice as strong as the C–C bond in ethane

Answer 3

C

Question 4

Explain why there is an attraction between a C=C double bond and Br2

Answer 4

C=C electron rich / area of high electron density
M1 ignore idea that C=C is negative or highly
electronegative
1
M2 Br-Br becomes polarised
1
M3 δ+ Br attracted to C=C

Question 5

Deduce the molecular formula of DEHP and state why a plasticiser is
added to PVC.
Molecular formula ____________________________________________
Why a plasticiser is added

Answer 5

add flexibility

The properties of polymers can be modified using a plasticiser. A plasticiser makes a polymer more flexible by pushing the different polymer chains away from each other. As the chains are now further away, the intermolecular forces between them are weaker and therefore the chains can slide over each other. This causes the polymer to be flexible and bend into different shapes.