SC20 Fuels
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Define hydrocarbon
A compound that contains hydrogen and carbon only
What is crude oil?
• complex mixture of hydrocarbons of different sizes • thick, sticky black liquid that is found in porous rock
What is crude oil used for?
• fuel for vehicles such as aircraft, ship, heating and power stations • feedstock or raw materials for the petrochemical industry
Define petrochemicals
Substances made from crude oil, such as poly(ethene) and other polymers
Define finite resource
Resources that are not made anymore (or are being made extremely slowly) which limits the amount available to us
Why is crude oil a finite resource?
It is being used up faster than it is being produced
Why is crude oil important fror the petrochemical industry?
• The fuels that are used in most modern methods of transport are all based on oil products • these are all product obtained from crude oil
Define non renewable
Fuels that are being used up faster than they can be formed
How is crude oil formed?
• ancient remains of microscopic animals and plants that once lived in the sea • became covered in layers of sediments • the high temperatures and pressure caused the sediments to turn into rocks, therefore trapping the gas and the oil
How do we separate crude oil into different hydrocarbon?
Using fractional distillation
Describe how crude oil is separated by fractional distillation
• crude oil enters fractionating column, so vapours rise • vapours with very high boiling points will immediately condense, into liquids lower down and are tapped off • vapours of hydrocarbons with low boiling points will rise up and condense at the top of the column
What are the different compounds obtained from crude oil?
• natural gas • petrol • kerosene • diesel oil • fuel oil • bitumen
Define fractional distillation
The separation of a liquid mixture into fractions differing in boiling point by means of distillation, typically using a fractionating column
What determines what fraction a molecule will go into?
The size and length of the hydrocarbon
Explain how the fractional distillation of crude oil works
The different hydrocarbons in crude oil have different boiling points, due to the differing chain lengths. This allows the hydrocarbons to be grouped into fractions of a similar boiling point, allowing for the separation of them
What is natural gas used for?
Domestic heating and cooking
What is petrol used for?
Fuels for cars
What is kerosene used for?
Jet fuel
What is diesel used for?
Fuel for some cars and trains
What is fuel oil used for?
Ships and power stations
What is bitumen used for?
Surfacing roads and roofs
What is common in each fraction
• similar properties • similar boiling points • similar chain lengths of hydrocarbons
Define viscosity
Refers to the ease of the flow of a liquid
Why does the boiling point increase as the chain length increases?
As the molecules get larger, the intermolecular forces of attraction between the molecules becomes greater as there is more surface area in contact between them. This means more heat is required to separate the molecules, leading to an increase in boiling point