FRACTIONAL DISTILLATION OF CRUDE OIL • a mixture of hydrocarbons What is crude oil? • hydrocarbons are compounds that contain hydrogen and carbon only • fractional distillation How is it separated? How does this work? • oil is vaporised by heating < 40 C 25°C° FUEL GASES passed into tower/column that is hotter at bottom than top Calor gas, LPG • C1-C4 • hydrocarbons cool and condense as they rise 40-90 C • as they have different boiling points 40°C ° GASOLINE C4-C12 petrol for cars • the smaller the molecule, the higher up the tower/column they reach 11090-160°C °C NAPHTHA petrochemicals C7-C14 160-250°C 200°C KEROSENE jet fuel C11-C15 250-350°C 300°C DIESEL (GAS OIL) C15-C19 fuel for diesel engines vaporised crude oil >350 350°C°C RESIDUE distilled further at lower > C20 pressures to give FUEL OIL, LUBRICATING OIL, WAXES and BITUMEN • a mixture Are the fractions pure substances or mixtures? How can you tell? • the fraction boils over a range of temperatures rather than one specific temperature Small Big hydrocarbons hydrocarbons Boiling points low high How does the size of the hydrocarbons affect its Flammability catch fire hard to ignite properties easily Cleanliness of clean smoky flame Viscosity runny viscous © www.CHEMSHEETS.co.uk 11-July-2017 Chemsheets GCSE 1230 1) Crude oil is a mixture of hydrocarbons. What are hydrocarbons. compounds that contain hydrogen and carbon only 2) The hydrocarbons in crude oil have different properties. Which of these properties does separation by fractional distillation depend on? different boiling points 3) Two of the hydrocarbons in crude oil are decane and pentane. H H H H H H H H H H H H H H H H C C C C C C C C C C H H C C C C C H H H H H H H H H H H H H H H H decane pentane Which of these molecules a) has the higher boiling point? decane b) is more runny? pentane c) catches fire more easily? pentane d) burns with the smokier flame? decane e) collects higher up the fractionating column? pentane 4) Kerosene is a fraction of crude oil used as fuel for aeroplanes. Is kerosene a pure substance or a mixture? Explain your answer. a mixture as the fraction boils over a range of temperatures rather than one specific temperature © www.CHEMSHEETS.co.uk 11-July-2017 Chemsheets GCSE 1230 .