Crude oil Flashcards
What is crude oil?
Crude oil is a fossil fuel made from the remains of dead biomass from millions of years ago.
What is fractional distillation?
It can be used to separate hydrocarbon fractions
What is fractional distillation?
It can be used to separate hydrocarbon fractions
Describe the process of fractional distillation
1) The oil is heated until most of it has turned into gas. The gases enter a fractionating column
2) In the column there is a temperature gradient (It’s hot at the bottom and gets cooler as you go up)
3) The longer hydrocarbons have high boiling points so they condense back into liquids and drain out of the column early on near the bottom where it is hotter.
4) The shorter hydrocarbons have lower a lower boiling point. They condense and drain out later on near the top of the column where it is cooler.
5) You end up with the crude oil mixture separated out into different fractions
What is crude oil used for?
- Modern transport (cars, planes, and trains)
- Feedstock to make new compounds such as lubricants and detergents
What does cracking mean?
Cracking means splitting up long-chain hydrocarbons
Why do we use cracking?
- Short-chain hydrocarbons are flammable and so make good fuels and are high in demand
- However, long-chain hydrocarbons are less flammable and form thick gloopy liquids like tar which are not useful
What type of reaction is cracking?
Cracking is a thermal decomposition reaction which means breaking molecules by heating them
Describe the process of catalytic cracking
1) Heat the long-chain hydrocarbons to vaporise them
2) Then the vapour is passed over a hot powdered aluminium oxide catalyst
3) The long-chain molecules split apart on the surface of the specs of catalyst
Describe the process of steam cracking
1) Heat long-chain hydrocarbons to vaporise them
2) Mix them with steam and then heat them to a very high temperature
