Products from oil

Question 1

What is cracking?

Answer 1

The breaking down of long-chain hydrocarbons (e.g. heating oil) into smaller ones (e.g. petrol)

Question 2

Why do we crack long-chain hydrocarbons?

Answer 2

The shorter chain hydrocarbons are more useful to use for fuel

Question 3

What happens when diesel, a long molecule is cracked?

Answer 3

Diesel –>(cracking) petrol + paraffin + ethene for plastics

Question 4

What type of reaction is cracking?

Answer 4

Thermal decomposition

The breaking down of molecules by heating them

Question 5

What is the process of cracking? (method)

Answer 5

1- Heat long-chain hydrocarbon
2- Vapour passed over a powdered catalyst at about 400-700 degrees celsius
3- Aluminium oxide is used as the catalyst
4- Long-chain products split apart (crack) on the surface of the specks of catalyst
5- Most of the products are alkanes and alkenes

Question 6

Show the cracking of kerosene…

Answer 6

Vaporised kerosene –>(Aluminium oxide catalyst)–> octane + ethene

Question 7

What is the test for discovering if a hydrocarbon is an alkane or an alkene (saturated or unsaturated)?

Answer 7

Bromine water test

• Bromine water is orange
• Hydrocarbons are colourless
• If the hydrocarbon is unsaturated then the bromine water when added will turn colourless, using up the free bonds until it becomes saturated

Question 8

What are the properties of alkanes?

Answer 8

• Saturated
• No space for more hydrogen atoms
• Single bonds

Question 9

What are the properties of alkenes?

Answer 9

• Unsaturated
• Carbon=carbon double bond
• Double bond can be broken to add more hydrogen atoms

Question 10

What is a monomer?

Answer 10

A small molecule used to make a polymer

Question 11

What is an addition polymer?

Answer 11

A polymer made up of similar monomers

Question 12

What are the processes involved from crude oil to polymerisation?

Answer 12

Crude oil –> Fractional distillation –> Cracking –> Polymerisation

Question 13

What does the monomer ethene form?

Answer 13

An addition polymer

Polythene (Poly(ethene))

Question 14

What is Poly(tetrafluoroethene) and what are its uses?

Answer 14

• Monomer= C2F4

- Inflammable, used for non-stick pans

Question 15

What is the monomer of Poly(chloroethene)?

Answer 15

C2H3Cl

Question 16

Why is ethene the smallest unsaturated hydrocarbon?

Answer 16

There has to be at least 2 carbon atoms to make a double bond with the ability to have free space for hydrogens

Question 17

How can we produce ethanol using ethene?

Answer 17

By reacting ethene with steam in the prescence of a catalyst

Hydration

Question 18

What are the benefits and drawbacks of using ethene to produce ethanol?

Answer 18

• Cheap, not much wasted

- Ethene produced from crude oil which is non-renewable and a fossil fuel (will become expensive as it runs out)

Question 19

What is ethanol used for?

Answer 19

Fuel for cars

chemical name for alcohol C2H5OH

Question 20

What are the benefits of ethanol?

Answer 20

• Renewable
• Clean burning
• Carbon neutral

Question 21

How is ethanol made from sugar?

Answer 21

• Sugar dissolved in warm water
• Add yeast
• Causes fermentation reaction
• Yeast converts sugar into ethanol

Sugar (glucose) –>(yeast) ethanol + carbon dioxide

Question 22

What are the advantages of using fermentation to make ethanol?

Answer 22

• Doesn’t require electricity
• Renewable source
• Needs lower temperatures and simpler equipment
• Can be used as quite a cheap fuel
• Sugar is a major crop grown all over the world and could provide more income to LICs who grow it

Question 23

What are the disadvantages of using fermentation to make ethanol?

Answer 23

• Gives off carbon dioxide as a by-product
• This greenhouse gas contributes to global warming
• Forests may have to be destroyed to make space for sugar plants
• Loss of crop land which could have been used for food
• Not very concentrated so would have to be distilled
• Needs to be purified

Question 24

What are the advantages of hydrating ethene to make ethanol?

Answer 24

• No by-products

- Continuous process

Question 25

What are the disadvantages of hydrating ethene to make ethanol?

Answer 25

• Uses up crude oil (non-renewable)

- Requires a catalyst

Question 26

What is polymerisation?

Answer 26

The joining together of many small alkene molecules (monomers) to form very large molecules called polymers

Question 27

Why is PET plastic (polyethylene terephthalate) used in drinks bottles?

Answer 27

• Strong
• Tough
• Light
• Waterproof
• (properties mean it can be used in hiking boots)

Question 28

What are designer polymers?

Answer 28

Polymers scientists have designed which are ‘smart’ in some way to make it useful

Question 29

What are light-sensitive plasters? (designer polymer)

Answer 29

Plasters made of a specific polymer layer which causes pain-free removal of the plaster

Question 30

How do light-sensitive plasters work?

Answer 30

When the plaster is ready to be taken off, remove the top layer of the plaster, exposing the bottom layer to light- the reaction causes the plaster to be removed without pain

Question 31

What are shape-memory polymers? (designer polymer)

Answer 31

Stitches that respond to body heat and eventually dissolve harmlessly into the body

Question 32

How do shape-memory polymers work?

Answer 32

Stitch is sewn loosely into the wound, it reacts to body heat and tightens with the correct amount of force, when the wound has healed, the stitches dissolve and are absorbed harmlessly by the body

Question 33

How does a polymer’s physical properties change in the way they are produced?

Answer 33

By changing the temperature and pressure of polmerisation

e. g.
- Poly(ethene) made at 200 degrees C and 2000 atmospheric pressure is flexible with a low density
- Poly(ethene) made at 60 degrees C and a few atmospheric pressure with a catalyst is rigid and dense

Question 34

Are most polymers biodegradable?

Answer 34

No

Not broken down by microorganisms, so they don’t rot

Question 35

What is an example of a polymer which is biodegradable and where is it used?

Answer 35

Corn starch

Packaging

Question 36

What is the best thing to do with non-biodegradable polymers after their first use?

Answer 36

Recycle them

• Conserves crude oil reserves a bit more (means the polymers will still be cheaper to produce than metal for a little bit longer whilst there is still more)
• Less energy wasted in producing more along with bad by-products
• Landfill means that the polymer material would still be there for 100s of years