in today's video we're going to take a look at crude oil and see how we can separate it into its different components using fractional distillation crude oil is a fossil fuel that we get from deep under the ground and is basically a mixture of lots of different compounds nearly all of these compounds though are hydrocarbons which contain only hydrogen and carbon and the most common type of hydrocarbons are alkanes which we covered in the last couple of videos now crude oil 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 then in the millions of years between then and now the high pressures and temperatures under the ground turned this organic biomass into crude oil as it formed this crude oil soaked into the rocks and was stored for millions of years but we can get it back out by drilling into the rock and sucking it up to the surface as crude oil takes so long to form it's effectively a finite resource and if we continue to extract and use it at the rate that we are now then one day we'll run out of it completely this is why we refer to fossil fuels like coal oil and gas as non-renewable fuels once we've extracted the crude oil from the ground we need some way to separate out all of the different hydrocarbons in the mixture because they each have different properties and so we'll use them for different things to do this separating we use a process called fractional distillation which involves heating the crude oil up and separating out different compounds by making use of the fact that the different compounds all have different boiling points the first step is to feed the oil into a chamber and heat it until most of it has turned into a gas we then pass this gaseous mixture into a fractionating column which is really hot at the bottom but gets cooler towards the top the idea is that these hot gases will then start to rise up the column but importantly as soon as they reach a region that has a lower temperature than their boiling point they'll condense into a liquid the hydrocarbons with the longest chains so the most carbons have the highest boiling points and so they'll quickly condense back into a liquid and drain out of the column early on because it's not hot enough to keep them in their gaseous states these are things like bitumen which we use to surface our roads and heavy fuel oil which can be separated further and used for things like heating oil fuel oil or lubricating oil the shorter chain hydrocarbons though have much lower boiling points so they'll stay they gas so much longer as they rise up the column until they finally reach a cool enough temperature that they condense into a liquid this gives us fuels like diesel and petrol which we're using cars and other road vehicles and kerosene which is used in jet engines some hydrocarbons though are so short and have such low boiling points that they stay as a gas the entire time for example lpg which stands for liquefied petroleum gas contains mainly propane and butane which are both very short chain alkanes if we compare these different groups or fractions the ones towards the top which are the shorter chains are the most flammable and so they tend to make the best fuels meanwhile the longer chain hydrocarbons here at the bottom are often poor fuels so are instead either used for something else or can be broken down into smaller hydrocarbons in a process called cracking which we'll take a look at in the next video the last thing to point out is that as well as all of these fairly direct uses that we mentioned here petrochemicals which is what we call all of these substances that we get from crude oil can also be used as feedstock which just means raw materials for the petrochemical industry you use them to make things like solvents lubricants polymers and detergents anyway that's all for this video so hope you found useful if you did then please do give us a like and subscribe and we'll see you next time