crude oil and fractional distillation

• Crude oil is a fossil fuel that is a mixture of many different compounds, with nearly all of them being hydrocarbons containing only hydrogen and carbon
• Crude oil is formed naturally from the remains of dead plants and animals, particularly plankton that died millions of years ago and were buried in the mud
• High pressures and temperatures under the ground turned the organic biomass into crude oil over millions of years
• Crude oil is a finite resource that takes a long time to form, making fossil fuels like coal, oil, and gas non-renewable
• Fractional distillation is used to separate the different hydrocarbons in crude oil based on their boiling points
• The process involves heating the crude oil until most of it turns into a gas
• The gaseous mixture is then passed into a fractionating column that is hot at the bottom and cooler towards the top
• Hydrocarbons with longer chains (more carbons) have higher boiling points and condense back into a liquid early on in the column
• Shorter chain hydrocarbons have lower boiling points and stay as gases longer, condensing into liquids towards the top of the column
• Different fractions obtained from fractional distillation include:

  • Bitumen and heavy fuel oil (longest chain hydrocarbons)
  • Diesel, petrol, and kerosene (shorter chain hydrocarbons)
  • LPG (liquefied petroleum gas) containing mainly propane and butane (very short chain alkanes)
• Shorter chain hydrocarbons towards the top of the column are more flammable and used as fuels, while longer chain hydrocarbons at the bottom are often used for other purposes or can be cracked into smaller hydrocarbons
• Petrochemicals obtained from crude oil can be used as feedstock for making solvents, lubricants, polymers, and detergents