3.12 Fractional Distillation Flashcards
What is crude oil?
A fossil fuel that we get from deep under the ground, its basically a mixture of lots of other compounds.
Which compounds make up crude oil?
Nearly all of them are hydrocarbons
How is crude oil formed?
It is formed naturally, from the remains of dead plants and animals, particularly plankton that died millions of years ago and were buried in the mud. In the millions of years between then and now, the high pressures and temperatures under the ground turned this organs biomass into crude oil. As it formed, this crude oil soaked into the rocks and was stored for millions of years
How do we get crude oil out of the ground?
By drilling into the rocks it is soaked into and sucking it back up to the surface
As crude oil takes so long to form, what type of resource is it classed as?
Finite resource
Why is crude oil being a finite resource significant?
Because it takes so long to form, if we continue to extract and use it at the same rate that we are now, then one day we will run out of it completely
What type of process do we use to separate the hydrocarbons in crude oil?
Fractional Distillation
How do we carry out fractional distillation? (4)
- Feed the oil into a chamber, the oil is heated until most of it has turned into a gas. The gases enter a fractioning column (and the liquid bit is drained off)
- The fractionating column is a tall column which has condensers coming off at various points
- The column is heated from the bottom so there’s a temperature gradient (its hot at the bottom and gets cooler as you go up)
- The longer hydrocarbons have ugh boiling points. They condense back into liquids and drain out of the column early on, when they’re near the bottom. The shorter hydrocarbons have lower boiling points. They condense and drain out much later on, near to the top of the column where it cooler
What are 2 examples of hydrocarbons that have high boiling points and condense early on in the fractional column? + uses
- Bitumen: used to surface our roads
- Heavy Fuel Oil: can be separated further and used for things like heating oil, fuel oil or lubricating oil
What are 3 examples of short hydrocarbons that condense at the end of the fractional distillation of crude oil? + uses
- Petrol: used in cars and other road vehicles
- Kerosene: used in jet engines
- Diesel: used in cars and other road vehicles
Some hydrocarbons are so short that they stay as a gas the whole time while in the fractionating column. What is an example of one?
LPG: (Liquified petroleum gas) contains mainly propane and butane which are both very short chain alkanes
What is a trend between the hydrocarbons with lower boiling points in crude oil?
They’re the most flammable so make the best fuels
What are the hydrocarbons with higher boiling points in crude oil used for?
- Either ‘something else’ or broken down into smaller hydrocarbons (cracking)
What is the name for all of the substances we get from crude oil when we carry out fractional distillation?
Petrochemicals
What else can petrochemicals be used for?
Feedstock: raw materials for the petrochemical industry, they use them to make things such as solvents, lubricants, polymers and detergents
