How crude oil was formed• Microscopic plants and animals die and fall to the sea bed• Layers of sand and mud form on top• Pressure and high temperature cause oil to form• Oil obtained by drilling
Oil is a fossil fuelOther fossils fuels are: Coal and Gas
Non-renewable Renewable Biofuels – ethanol and biodiesel made from plants
Crude oil is amixture of a verylarge number ofcompounds.These compoundscan be separatedby distillation.
The Fractional Distillation of Crude Oil Average number of C atoms in chain Fraction Boiling pt. Liquid petroleum < 25oC 3 gas 40o Petrol (gasoline) 25 – 60oC 8 C Very hot crude oil is pumped into Naphtha 60 – 180oC 10 the fractionating column where the hydrocarbons separate180 – by their boiling points, out 220oC 12 Paraffin rising through the column until they get cold enough Diesel to condense. The compounds that 220 – 250oC 20 condense at a particular temperature are called a FRACTION. Fuel oil 250 – 300oC 40 Lubricating oil 300 – 350oC 80 350oC Bitumen > 350oC 120HeatedCrudeOil
Most of the compounds in crude oil consist of molecules made up of hydrogen and carbon atoms only (hydrocarbons). Most of these are saturated hydrocarbons called alkanes. CH4 C2H6 C3H8Write the chemical In general:formula for thesealkanes CnH2n+2 C4H10
Alkane molecules can be represented in the followingforms:
FuelsMost alkanes are used as fuels to produce useful forms ofenergy.When completely burned alkanes form carbon dioxideand water.
Equations for combustion CH4 + 2 O2 CO2 + 2 H2Omethane oxygen carbon water dioxide C3H8 + 5 O2 3 CO2 + 4 H2O C2H4 + 3 O2 2 CO2 + 2H2O
Most fuels, including coal, contain carbon and/orhydrogen and may also contain some sulfur. The gases released into the atmosphere when a fuel burns may include: •carbon dioxide GLOBAL WARMING •water (vapour) •carbon monoxide •sulfur dioxide and ACID RAIN •oxides of nitrogen. Solid particles (particulates - sometimes called soot) may also be released. GLOBAL DIMMING