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Crude oil
Chemistry
Question | Answer |
---|---|
What is crude oil? | A thick sticky black substance found under the ground or sea in certain parts of the world. |
Crude oil has to be refined before it is useful. How? | By fractional distillation - it is split into different fractions. |
Where does it take place? | In a fractionating column. |
Temperatures? | The column is hot at the bottom and gradually becomes cooler near the top. |
Process. Firstly... | The crude oil is heated until it vapourises. The vapour is then fed into the bottom of the column. |
Then, what happens to the hydrocarbons with very high boiling points? | They immediately turn into liquids and are tapped off at the bottom of the column. |
However, what happens to the hydrocarbons with boiling points lower than 400 degrees? | They remain as gases and rise up the column. As they rise, they cool down. |
The temperature at the bottom of the column is: | 400 degrees celcius. |
The temperature at the top of the column is: | 40 degrees celcius. |
What's different about the different fractions? | They condense at different heights according to their different boiling points. |
What happens to a fraction when it is condensed? | It is tapped off as a liquid. |
Which fraction has the lowest boiling point and what happens to it? | Refinery gases and it remains as a gas and comes out of the top of the column. |
Which fraction has the highest boiling point? | Bitumen. |
From the hottest to the nottest: | Beware, freddy ditched katie glass recently. |
Properties. Carbon atoms? | Fractions with higher boiling points have a higher number of carbon atoms in each molecule. (they are longer chain hydrocarbons, shorter chain hydrocarbons have lower boiling points). |
Properties. Viscosity? | Fractions with higher boiling points are more viscous. |
What does viscous mean? | Thick, sticky. |
Refinery gases are used for: | bottled gas for camping. |
Gasoline: | Petrol. |
Kerosene: | Fuel for aeroplanes, oil for central heating boilers & parrafin for small lamps. |
Bitumen: | Road surfaces & covering flat roofs/buildings. |
Which fractions are more in demand? | Shorter chain hydrocarbons. |
To produce more shorter chain hydrocarbons, we use a process called... | CRACKING. |