3.4 Alkenes

Question 1

What is electrophillic addition?

Answer 1

The closeness of the electron rich bond causes a dipole within the halogen, hydrogenhalogen, H2SO4. This creates a carbocations

Question 2

What is hydrogenation?

Answer 2

Is used in making margarine
H is added to c=c
200c
10Å
Nickel catalyst

Question 3

How is bromine water used to test for the presence of an alkene?

Answer 3

Alkene+Bromine-> bromoalkane
Bromine turns from brick red to colourless. This is due to electrophillic addition occurring.
It is semi quantities

Question 4

What are addition polymers?

Answer 4

The double bond is opened to from polymers and long chains.

Ethane-> poly(ethene)

Question 5

What are the properties of polymer alkenes?

Answer 5

Very Unreactive
Strong covalent bonds
Branching reduces the intermolecular forces
Plasticisers can be added to make the polymer bendier by pushing the neighbouring chains further apart.

Question 6

What is the stability of carbocations?

Answer 6

Primary - 1R group
Secondary- 2R groups
Tertiary- 3R groups

The more R groups the more stable and the more likely to be the final product.

Question 7

What are alkenes?

Answer 7

Unsaturated hydrocarbons. With a double bond which has a high electron density