Crude oil is called 'crude' because is a mixture of many different hydrocarbons. We refine the oil by separating it into molecules with a similar number of carbon atoms. These parts are known as __________. This separation process is called __________ distillation, and is done in a __________ column as a continuous process.
Some properties of hydrocarbons depend on the size of their molecules, including their boiling point. Heated crude oil is pumped into the bottom of the column and the different fractions are 'tapped off' from different plates. Each plate is maintained at a different temperature, with the top being __________ than the bottom.
The longer the hydrocarbons chain the __________ its boiling point. This is due to the long hydrocarbons being able to wrap around each other. It takes more energy to shake them apart to allow them to evapourate into a gas, hence the required higher temperature. The wrapping around of chains also affects the viscosity of the fraction. The longer the chain the longer it takes to pour the liquid.
Flammability is how easily something will burn or ignite. Small hydrocarbon chains have a higher degree of flammability - they are more flammable because they have a higher proportions of carbon-hydrogen bonds compared to carbon-carbon bonds, for the same number atoms. Carbon-hydrogen bonds are easier to break than carbon-carbon bonds and so short chains are easier to start the chemical reaction of combustion.