Addition Of Alkenes

Question 1

Test for unsaturation

Answer 1

• Use bromine water
• Bromine adds across double bond
• Solution colourless
• So Alkene

Question 2

What does polymer show

Answer 2

Long chain of alkene with C-C not C=C

Question 3

What does monomer show

Answer 3

• Shows repeating part of alkane with C=C
~ no bracket just n on right

Question 4

Repeating unit

Answer 4

•One section of alkene
• No double bond
• Bracket

Question 5

Property of long chain alkene

Answer 5

•Larger number of C-H and C-C
•Non polar, strong, lots of vdw
•Difficult to break and unreactive

Question 6

What is PVC and how to make it flexible

Answer 6

•Rigid polymer
~chains attracted by vdw

•PVC + plasticiser = flexible PVC
~ small molecules fit between polymer chains
~ make them move further apart
~intermolecular forces weaken
~ chains slide over each other

Question 7

Uses of low density and high density polyethene

Answer 7

•HDPE
~ higher mp
~ low temp & pressure
~ regular parttern
~ crates, buckets, bottles

•LDPE
~ flexible & stretch
~ high temp & pressure
~ irregular pattern
~ plastic bags, electrical insulation

Question 8

What is polymerisation

Answer 8

• joins identical monemers
• to make polymers

Question 9

Physical properties of alkanes

Answer 9

• weak vdw
• as molecules increase, bp increases
•insoluble in water
•branching lowers pb as more SA