Alkenes

Question 1

What makes the electrophile attracted to the double bond of alkenes?

Answer 1

They are:
- positive
- electron deficient
- so are electron pair acceptors

Question 2

What do double bonds have?

Answer 2

High electron density

Question 3

How to determine if product is minor or major?

Answer 3

• It is determined by the stability of the carbocation intermediate
• The more alkyl groups, the more stable

Question 4

How do alkyl groups stabilise the carbocation intermediate?

Answer 4

They push electrons towards the carbocation intermediate, thus stabilising it.

Question 5

What are the molecules that react with alkenes? And the molecule for test of alkenes?

Answer 5

• Hydrogen halide - HBr
• Sulfuric acid (H2SO4)
• Br2

Question 6

Alkenes are what?

Answer 6

unsaturated hydrocarbons

Question 7

Why are addition polymers unreactive?

Answer 7

• C-H bonds are strong
• they are non-polar

Question 8

What is (PVC) poly(chloroethane) made from?

Answer 8

long, closely packed polymer chains

Question 9

What do plasticisers do for PVC?

Answer 9

• make them more flexible
• weakens intermolecular forces between chains so they can slide more between each other, thus bend

Question 10

What are the uses of PVC?

Answer 10

• for drain pipes
• electrical cable insulation
• clothing

Question 11

POLYALKENE PROPERTIES
What intermolecular forces do polyalkenes have? Describe its nature.

Answer 11

• polyalkenes are nonpolar so they only have van der waals forces
• longer chains => closer => more VDW forces

Question 12

What is a polymer?

Answer 12

Large, long chain molecules made up of monomers, joined by covalent bonds

Question 13

How does a stereoisomer arise?

Answer 13

• exist because of non-rotatable C=C bond
• when there are 2 different groups attached to either side of the C=C bond

Question 14

What is one characteristic of the alkyl groups that make it stabilise the carbocation intermediate

Answer 14

They are electron releasing