Crude Oil + Fractional Distillation

What is required for the formation of crude oil?

• High pressures

• High temperature

• Millions of years

• Anaerobic conditions

• Dead marine organisations

How does crude oil form?

1. Millions of years ago. dead bodies of marine fauna and flora formed a thick layer of sediment on old sea beds

2. This layer of organic matter was buried by huge deposits of mud and rock granules

3. From high heat + pressure from layer of rocks overhead, the organic remains partly decay over millions of years, with the absence of oxygen forming a pocket of gas + oil.

4. The gas + oil passes through the porous rock and collected beneath the non porous rock

How is crude oil extracted fromteh ground?

• Extracted from geological strata (sediment) by drilling down to deposits and pumping oil back to the surface.

• These strata are normally accompanied by deposits of natural gas and methane

What is crude oil?

Finite resource of a mixture of hydrocarbons, a natural and renewable resource

How does fractional distillation of crude oil occur?

1. Oil is vapourised + passed into a fractionating column

2. Fractionating column has a temp gradient (hot at the bottom, cold at the top)

3. The different hydrocarbons travel up the column and are separated depending on there boiling points

4. The longer chain hydrocarbons condense nearer the bottom of the column and the shorter chain hydrocarbons condense near the top of the column

Are fractions pure substances or mixed?

• They are a mixture because they melt at a range of boiling points and have a range of hydrocarbons

How is boiling point affected by size of hydrocarbons?

• Small hydrocarbons have a low boiling point because they have fewer electrons leading to a weak intermolecular force

• Large hydrocarbons have a high boiling point because they have more electrons leading to a strong intermolecular force

How is flammability affected by size of hydrocarbons?

• Small hydrocarbons have a high flammability because they are more volatile and easily mix and react with air

• Large hydrocarbons have a low flammability because they are less volatile and less easily mix and react with air

How is the cleanliness of the flame affected by the size of hydrocarbons?

• Small hydrocarbons have a cleaner flame

• Larger hydrocarbons have a smokier flame

How is the viscosity affected by the size of hydrocarbons?

• When a liquid is poured, the molecules have to pass each other, the easier it is, the runnier the liquid.

• Small hydrocarbons have a low viscosity because they are more spherical and tend not to get tangled increasing the runniness of the liquid

• Large hydrocarbons have a high viscosity because they will get entangled, reducing the runniness of the liquid

How is the colour affected by the size of hydrocarbons?

• Small hydrocarbons are colourless

• Large hydrocarbons are orange / brown