Fractional Distilation

Question 1

What is crude oil?

Answer 1

•it is a fossil fuel and a finite resource ( a resource that will eventually run out) drilled up from rocks
•it is also a mixture made up of lost if different hydrocarbons most of which are alkanes

Question 2

How was crude oil formed?

Answer 2

1)It was formed from the remains of plants and animals,mainly plankton, that died millions of years ago and were buried in mud
2)over millions of years, with high temperature and pressure, the remains turn to crude oil which can be drilled from rocks where it is found

Question 3

How is fractional distilation used to seperate the different compounds in crude oil?

Answer 3

*the oil is heated then vaporised.The vapour enters a fractionating column
*in the column there is a temperature gradient meaning it is hot at the bottom and gets cooler as you go up so the vapour cools and condenses at different temperatures
*the longer hydrocarbons have high boiling points. They condense back into liquids and drain out of the column early on they are 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 is cooler
*Therefore you end up with the crude oil mixture separated into different fractions. Each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms so have similar boiling points