C1.5 Other Useful Substances from Oil Flashcards
Why is a process called cracking taken place after fractional distillation?
Because long-chain hydrocarbons form thick gloopy liquids which aren’t that useful
What does cracking do?
It creates shorter chain hydrocarbons from long-chain hydrocarbons
What products can be made from cracking? (3)
Fuels, like petrol for cars and paraffin for jets, and substances like ethane can be produced which is needed to make plastics
How does cracking work? (3)
Molecules are broken down by heat -
- The long-chain hydrocarbons are vaporised into gas
- The gas is passed over a powdered catalyst at about 400°C-700°C
- The long-chain molecules split apart on the surface of the specks of catalyst
What type of reaction is cracking?
A thermal decomposition reaction
What is the main catalyst used in cracking?
Aluminium Oxide
What is an alternative method of cracking?
By mixing the vaporised long-chain hydrocarbons with steam and heating it to very high temperatures
What are the products of cracking forms of?
Alkanes and alkenes
What advantages are there to using crude oil? (6)
They release lots of energy when burnt, they burn cleanly, can be used to make plastics, there are already petrol stations all over the world so it is for the customer to obtain, it’s cheaper than other sources of energy and unlike other sources of energy, crude oil is reliable
What affects does crude oil have on the environment?
Oil spills can occur which pollute water and poison sea creatures, also burning the oil as a fuel is thought to be the major cause of global warming, acid rain and global dimming
Crude oil is non-renewable, what does this mean?
It means that it will soon run out completely, this will mean that a new reliable source will need to be found to satisfy energy demands in the world
When crude oil runs out, what will need to change?
Many things like car engines, will need to be able to run off the new source of energy
Many people think we should stop using crude oil now, why?
We should conserve and only use it for essentials like chemicals and medicines
Why do many people believe there is no need to change the world’s primary energy source?
Because technology is constantly improving so less crude oil may be needed in the future anyway
What are alkenes?
Hydrocarbons which contain a carbon-carbon double covalent bond
What does the double bond in alkenes mean?
It means that alkenes are unsaturated - the double bonds can open up, allowing the carbon atoms to bond with other atoms
What are the first 2 alkenes?
Ethene C2H4, and propene C3H6
What is the general formula of alkenes?
CnH2n
What is the test for alkenes?
By adding the substance to bromine water - an alkene will decolourise the (orange) bromine water, this is because the double bond has opened up and formed bonds with the bromine
How is ethanol made from ethene?
In a hydration reaction - ethene is reacted with steam in the presence of a catalyst to make ethanol
What are the current benefits of making ethanol from ethene? (1)
Ethene is currently very cheap - however, as it comes from crude oil, it is slowly running out and prices will increase
What alternative methods are there for making ethanol?
Fermentation
What is the word equation for fermentation?
Sugar ==> carbon dioxide + ethanol
What benefits does fermentation have over making ethanol from ethene? (4)
It is at a lower temperature, so less energy is used, so less money is spent, less CO2* is produced and sugar is renewable source which is grown in 3rd world countries which brings money into their communities/ it’s an alternative for expensive petrol
What disadvantages are there to the fermentation method of making ethanol? (3)
The ethanol produced needs to be purified and it isn’t very concentrated, so you need to distil it to increase its strength. Also, there are concerns that growing more sugar, results in deforestation
What is polymerisation?
Joining lots of small alkene molecules (monomers), to for very large molecules (polymers)
How are polymers named after their monomers?
Polymers are just the name of the monomer with ‘poly’ in front of it
How do you draw a monomer from a polymer?
Remove the bonds from either side + brackets, and add the carbon-carbon double bond
What affects a polymers properties?
The monomers it’s made from, and how it’s made e.g. poly(ethene) made at 2000atm and 200°C is flexible + has a low density, but poly(ethene) made at 60°C, low pressure and a catalyst is rigid and dense
What are modern uses of polymers?
Waterproof coating, packaging materials, tooth fillings, wound dressings, and memory foam mattresses
What is memory foam a form of? How does it work?
A smart material, it gets softer as it gets warmer
What are the problems with using polymers? (2)
They aren’t biodegradable, they are just thrown in landfills and stay there for years, currently polymers are cheaper than metals, but as crude oil decreases, the price of polymers will increase
How are polymers being made to be biodegradable?
By containing corn starch
