Alkenes

Question 1

How many bonded pairs do double bonds contain?

Answer 1

2

Question 2

Define the term ‘electrophile’?

Answer 2

Electron pair acceptor

Question 3

Which two bonds are present in a double carbon-carbon bond?

Answer 3

Pi bond

Sigma bond

Question 4

Which bond breaks in electrophillic addition? Why

Answer 4

Pi bond because it is more exposed than the sigma bond and therefore more easily accessible

Question 5

Why must an electrophile contain a positive region?

Answer 5

To attract the negative electron rich centre as opposites attract

Question 6

What is an addition reaction?

Answer 6

A reaction whereby two molecules join to make a larger molecule

Question 7

How do we identify which part is slightly negative and which is slightly positive in an electrophile which consists of two elements?

Answer 7

The most electronegative atom carries the slightly negative charge and thus, the other atom has the positive charge

Question 8

What does a curly arrow represent?

Answer 8

Movement of electrons

Question 9

What type of product is formed in hydrogenation (Alkenes with hydrogen)?

Answer 9

Alkanes

Question 10

What are the conditions required for hydrogenation?

Answer 10

Nickel catalyst

150C

Question 11

What type of product is produced in halogenation (addition of a group 7 element to an Alkene)?

Answer 11

Haloalkane

Question 12

What test is carried out when testing for an Alkene?

Answer 12

Addition of bromine water to solution

Question 13

What is observed when bromine water is added to an Alkene?

Answer 13

Colour change of orange to colourless

Question 14

Which type of bonds are unsaturated?

Answer 14

Double bonds

Question 15

Which type of bonds are saturated?

Answer 15

Single bonds

Question 16

What is the hydration of ethene?

Answer 16

Addition of steam to ethene to produce an alcohol

Question 17

What does the reaction of an alkene and steam produce?

Answer 17

An alcohol

Question 18

What are the conditions for the hydration of an alkene?

Answer 18

Steam and gaseous alkene
High temperature (300C)
High pressure
Conc phosphoric acid catalyst

Question 19

When there is a combination of possible products due to an unsymmetrical alkene, how do we decide which is the major product?

Answer 19

Choose the product with the most stable carbocation (eg tertiary is more stable than secondary and secondary is more stable than primary; choose the most stable)

Question 20

What is addition polymerisation

Answer 20

When an alkene becomes saturated under specific conditions to form long chain polymers

Question 21

What is a monomer

Answer 21

A small molecule

Question 22

What is a polymer

Answer 22

A long chain molecule containing many monomers

Question 23

Give the conditions required for addition polymerisation

Answer 23

High temperature
High pressure
Catalyst

Question 24

How do you name a polymer made from a monomer

Answer 24

Same with poly in front of it

Question 25

How are repeat units displayed in addition polymerisation

Answer 25

Monomer inside brackets

Question 26

What are the conditions for hydration of ethene?

Answer 26

Catalyst H3PO4

Steam

Question 27

State two ways ethanol can be manufactured on a large scale

Answer 27

Fermentation

Hydration of ethene

Question 28

Out of fermentation and hydration of ethene in the production of ethanol, which is more sustainable?

Answer 28

Hydration of ethene has a higher atom economy
Fermentation does not require high temperatures and pressures so lower energy required
Ethene is created from crude oil which is non-renewable and is finite
So overall, fermentation is more sustainable

Question 29

How is atom economy calculated

Answer 29

Total of desired products / total of all products x100