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AS chemistry UNIT 2 module 1 > Hydrocarbons from crude oil > Flashcards

Flashcards in Hydrocarbons from crude oil Deck (6)
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1
Q

How is crude oil refined in a distillation plant?

A

1) The complex mixture of hydrocarbons in crude oil is first separated into fractions.
2) Each fraction consists of a mixture of hydrocarbons with similar boiling points.
3) Pure liquids have a fixed boiling point, a pure hydrocarbon can be obtained by further distillation of a crude oil.

2
Q

What is the definition of fractional distillation?

A

The separation of the components in a liquid mixture into fractions which differ in boiling point(and hence chemical composition) by means of distillation,typically using a fractionating column.

3
Q

How does fractional distillation work?

A

1) Crude oil vaporised
2) gasses pass up the column
3) Gases reach a temperature that is lower than their boiling points. Here, the vapour condenses to a liquid. The liquids are then tapped off into storage containers.

4
Q

What happens to the fractions contained for the crude oil?

A

They can be used as fuels or may be further processed to make petrochemicals. The fractions can also be distilled further to form pure liquids in other fractionating columns.

5
Q

What is the effect of chain length with the boiling points of alkanes?

A

As the chain length increases there are more points of contact leading to more van der Waal’s forces between molecules.

6
Q

What does the effect of branching have on the boiling points of alkanes?

A

Branched molecules have fewer points of contact and are further apart than unbranched molecules so there are fewer intermolecular forces.