Unit 9H Lesson 8 Fractional Distillation Objective: to learn how crude oil separated into useful chemicals.

Crude Oil When oil comes out of the ground it is a mixture of different chemicals like petroleum gases, petrol, and kerosene. Each one of these chemicals has useful properties but not when they are all mixed together. In order to separate these chemicals the oil must undergo a process known as fractional distillation.

What is Distillation Distillation is a way of separating substances which are mixed together. If you were to mix alcohol and water together you could separate the two substances by distillation. The process would work like this: –Heat the mixture when it reaches 78 °C the alcohol will boil. –When the alcohol boils it will turn to gas. –The gas will rise out of the mixture. Because water boils at 100 °C it remains a liquid. –The gaseous alcohol is then trapped and when the temperature is lowered it will turn back into a liquid. Observe distillation demonstration.

The Fractional Distillation of Crude Oil Oil is made up of several different substances but the most valuable is petrol. Oil is put through three different processes to get as much petrol as possible: –Cracking: fuel oils are polymers so they can be heated and broken down to monomers. –Re-polymerization: the monomers are then passed over a catalyst and put back together into polymers. Some of these polymers will form petrol. –Distillation: the fuel oils are then distilled to separate them. Another way of looking at this process is to say that fuel oils like kerosene are broken up and then put back together again as petrol. Fractional Distillation

Work to Do Read the second half of page 104 Look at figure 3 page 105 Answer questions 8-11 page 105 Homework –Define the following keywords: Polymerisation, cracking, distillation, evaporation, petroleum