Fractional distilation & petrochemicals

• -crude oil as a mixture is not a very useful substance

  the different hydrocarbons that make up the mixture(fractions- each consists hydrocarbons)are enormously valuable

  -The fractions in crude oil (petroleum) are separated from eachother in a process called fractional distillation

  -most fractions contain mainly alkanes
• Fraxtional Distiliation (Crude Oil)

  *Crude oil is evaporated

  *Vapours from evaporation are fed into fractionating column

  *Column cool at top & hot at bottom

  *Gasses condense when they reach their boiling point

  *Different fractions are collected as liquids at different levels

  *Each fraction is a mixture of hydrocarbons with similar boiling points
• Petrochemical industry

  petrochemical industry is hugely important for modern society and development

  -fractions can be processed to produce fuels/feedstock for petrochemical industry including:

  *polymers (alkenes)

  *lubricants

  *solvents

  *detergents
• fractional distilation order

  LPG (cooking in house)

  Petrol (cars)

  Kerosene (jet fuel)

  Diesel oil (vans)

  Heavy fuel oil (powers ship stations)

  Bitumen (surfacing roads/roofs)

  *longer alkanes have higher boiling points so they recondense lower down column, high amounts of energy requires to overcome strong intermolecular forces
• alkane combustion

  complete

  fuel + oxygen --> carbon dioxide + water

  incomplete

  fuel + oxygen --> carbon/carbon monoxide + water (POISONOUS)
• difference in alkanes

  shorter alkanes are more flamable

  longer chained alkanes have higher viscosity (thicker