Topic 8: Fuels and Earth Science Flashcards
What is crude oil?
A complex mixture of lots of different hydrocarbons (mostly alkenes)
Is crude oil a finite resource?
Yes
What are hydrocarbons?
Compounds that only contain hydrogen and carbon atoms
What happens as the length of the hydrocarbon chain increases?
Boiling point increases
Viscosity increases
Ease of ignition decreases
What is complete combustion?
A reaction that occurs when a fuel reacts with plenty of oxygen
What is the complete combustion reaction?
Hydrocarbon + oxygen —> carbon dioxide + water
Why are hydrocarbons used as fuels?
When they combust, they release a lot of energy
What is a homologous series?
A family of molecules which have the same general formula and share similar chemical properties e.g. alkanes
What is fractional distillation?
A process used to separate the hydrocarbons in crude oil into fraction according to their boiling points
Each fraction has different uses
How does a fractionating column work?
- Crude oil is heated until most of it has evaporated
- Longer hydrocarbons have higher boiling points so condense near the bottom of the column
- Shorter hydrocarbons have lower boiling points so condense near the top of the column
What are the fractions of crude oil (starting with the fraction produced at the top of the column)?
Gases
Petrol
Kerosene
Diesel oiI
Fuel oil
Bitumen
What are gases used for?
Domestic heating
Cooking
What is petrol used for?
Car fuel
What is kerosene used for?
Aircraft fuel
What is diesel oil used for?
Fuels cars and trains
What is fuel oil used for?
Fuels ships and power stations
What is bitumen used for?
Surfacing roads and roofs
What fractions of crude are non renewable?
Petrol
Kerosene
Diesel oil
What is cracking?
Breaking down long chain, saturated hydrocarbons (alkanes) into shorter, more useful molecules
Why is cracking done?
There is a higher demand for fuels with shorter carbon chains
Shorter hydrocarbons are more useful
What is the equation for cracking?
Long chain alkane —> shorter chain alkane + unsaturated alkene
How is cracking done?
Done by heating the alkane with an aluminium oxide catalyst