Describe the process of cracking
Long chain alkanes are heated with a catalyst
What is an alkene?
It’s a hydrocarbon with at least 1 double bond
What is the general formula for an alkene?
CnH2n
What happens when alkenes react with bromine water?
The bromine water changes from orange to colourless
Draw a diagram representing the process of polymerisation of ethene
H H H H H H
| | | | | |monomers C=C + C=C + C=C ->
| | | | | |
H H H H H H
ethene ethene ethene
H H H H H H
| | | | | |
polymer -C-C-C-C-C-C-
| | | | | |
H H H H H H
polyetheneWhat uses do we have for polymers?
- Plastic bags
- Plastic bottles
- Coating on electricity wires
- Buckets + Crates
- Window frames
- Nonstick coating on pans
Why is it important to recycle polymers?
- Plastics are not biodegradable
- Not recycling creates a build up in landfill sites
What is cracking and why is it necessary?
It is when a large alkane is made into a smaller alkane and an alkene.
It’s necessary because there is more demand for smaller, more useful hydrocarbons
Name and describe 3 smart polymers
- Lycra, a stretchy material used to make clothing. Doesn’t get affected from sweat and detergents
- Kevlar, an artificial fibre used to make body armour. It’s flexible, strong and tough
- Gore-Tex, an artificial fabric that keeps the rain out but lets sweat pass through. It’s waterproof and ideal for sports and outdoor clothing
What are the two methods of producing ethanol?
- By reacting steam with ethene at a moderately high temperature and pressure in the presence of a catalyst, phosphoric acid
- Fermentation, which is carried out in a solution using yeast at about 37*C
What is the word equation for producing alcohol from ethene?
Ethene + steam ——–> ethanol
Phosphoric acid
What is the word equation for producing ethanol from sugar?
Sugar–> ethanol + carbon dioxide
Yeast
What is the advantage of using fermentation?
-Uses corn and sugar cane (renewable resources)
What are the disadvantages of fermentation?
- Is a batch process, which needs a lot of workers
- Produces impure ethanol, and is purified by distillation
- Needs a temperature of 30-40*C
- Is a slow reaction
What are the advantages of using hydration?
- Is a continuous process so is less labour intensive
- Produces pure ethanol
- Is a fast reaction
What are the disadvantages of using hydration?
- Uses crude oil, which is a non renewable resource
- Requires a temperature of 300*C and high pressure
What are some uses of ethanol?
- Alcoholic drinks
- Fuel
- Solvent
- Disinfectants
- Perfumes
What is the process called hydration?
Making alcohol (ethanol) from ethene
What is the process called fermentation?
Making alcohol (ethanol) from sugar
What happens when long chain hydrocarbons are cracked?
A short chain alkane and alkene are produced
Why are hydrocarbons cracked?
~ Short chain alkanes are more useful fuels
~ Short chain alkenes can be used to make polymers
What is polymerisation?
When short chain alkenes (monomers) join to form long chain alkenes (polymers)
What is global dimming?
The reduction of light reaching earth due to particulates (soot) produced when some hydrocarbons burn
What does incomplete combustion produce?
Carbon monoxide, a poisonous gas
