C14 Alkenes

Question 1

What is an alkene?

Answer 1

Alkenes are unsaturated hydrocarbons and they contain a double c-c bond

Question 2

What is the general formula of alkenes?

Answer 2

CnH2n

Question 3

What is a property that double bonds contain in alkenes?

Answer 3

Double bonds have a high electron density and this makes alkenes fairly reactive making it susceptible to attack from electrophiles

Question 4

What are the observable changes for the test for alkenes using bromine water?

Answer 4

Turns the solution from orange-brown to colourless

Question 5

What is the main mechanism that occurs when alkenes are used?

Answer 5

Electrophillic addition

Question 6

Are electrophiles electron donors or acceptors?

Answer 6

These are electron acceptors

Question 7

What are electrophiles?

Answer 7

They are electron pair acceptors that are deficient in electrons and are attached to the double bond

Question 8

Name some of the most common electrophiles

Answer 8

HBr
Br2
H2SO4

Question 9

What do these common electrophiles produce?

Answer 9

They can be used to form alkyl hydrogensulphates or halogenoalkanes

Question 10

What is the amount of 2 products determined by?

Answer 10

It is determined by the stability of the carbocation intermediate

Question 11

What happens when more alkyl groups are bonded to the carbocation?

Answer 11

A more stable intermediate and this is due to the groups pushing electrons towards the positive carbocation stabilising it

Question 12

A more stable carbocation =

Answer 12

More likely it will form

Question 13

In order of least to most stable order carbocations

Answer 13

Primary
Secondary
Tertiary

Question 14

What do alkenes react with to form alkyl hydrogen sulfates?

Answer 14

Cold concentrated sulfuric acid

Question 15

How can alcohol be made via using alkyl hydrogen sulfates with sulfuric acid?

Answer 15

By adding cold water to warm alkyl hydrogen sulfate it will form a alcohol and reform sulfuric acid

Question 16

How is the process of making an alkyl hydrogen sulfate with sulfuric acid done?

Answer 16

Via Hydrolysis

Question 17

What does sulfuric acid acts as and why?

Answer 17

It acts as a catalyst as it is reformed

Question 18

What are addition polymers?

Answer 18

Addition polymers are produced from alkenes where the double bond is broken to form a repeating unit

Question 19

What is key to show when displaying a addition polymer?

Answer 19

The repeating unit must always be shown with extended bonds through the brackets showing that it bonds to other repeating units

Question 20

What type of polymers form under high pressure and temperature?

Answer 20

Branched chain polymers are produced with weak IF

Question 21

What type of polymer is produced under lower temperature and pressure?

Answer 21

Straight chain polymers with strong IF as they are closer together so more VDW

Question 22

What are polymers?

Answer 22

They are unreactive hydrocarbon chains with multiple strong, non polar covalent bonds

Question 23

What are plasticisers and what are they used for?

Answer 23

They added to polymers to change their properties

Question 24

How do plasticisers work t?

Answer 24

They make the polymers more flexible by allowing the polymer chains to slide between and push them apart

Question 25

Name an example of how and where plasticisers used?

Answer 25

Plasticisers are used in PVC as pvc is generally very hard and brittle used in drainage pipes but when plasticisers are used pvc is more flexible being used in electrical insulation

Question 26

Name a use of polymers

Answer 26

Shopping bags via poly(ethene))

Question 27

Why are addition polymers not biodegradeable?

Answer 27

Due to the unreactive nature of the bonds it cannot be broken down