Section 8 - Fuels & Earth Science Flashcards
What is crude oil?
A complex mixture of lots of different hydrocarbons found underground formed from the remains of plants and animals.
What are hydrocarbons?
Compounds made of only hydrogen and carbon.
How are the carbon atoms in the hydrocarbons found in crude oil often arranged?
Often as chains or rings
What are the various parts of crude oil called?
Fractions.
What type of hydrocarbon is the most common in crude oil?
Alkanes.
What process is used to separate the parts of crude oil?
Fractional distillation.
how does fractional distillation work?
The different fractions in a mixture condense at different temperatures, so the mixture is heated until most of it turns into gas. due to a temperature gradient in the fractionating column, the gasses condense at different heights, separating the mixture into its fractions.
describe the temperature gradient in a fractionating column.
The column gets cooler going up the column.
Describe the trend between hydrocarbon length and their boiling and melting points.
Longer hydrocarbons have higher boiling and melting points.
List some crude oil fractions, their approximate number of carbon atoms and their uses.
3, gases, used in domestic heating and cooking.
8, petrol, used as fuel for cars.
15, kerosene, used as aircraft fuel.
20, diesel oil, used as fuel for some cars and larger vehicles like trains.
40, fuel oil, used as fuel for large ships and some power stations.
70, bitumen, used to surface roads and roofs.
What is a homologous series?
A family of molecules which share a general formula and have similar chemical properties.
What are some examples of a homologous series?
Alkanes and alkenes.
Why does hydrocarbon size affect the molecule’s properties?
Longer hydrocarbons have more intermolecular bonds between them because there are more bonds it takes more energy to separate the molecules from another, this raises the boiling points and melting points as well as the viscosity of the molecules, it also makes them harder to ignite than smaller hydrocarbons as well.
How do fuels release energy?
Through combustion reactions.
What are the products of a complete combustion reaction?
Carbon dioxide and water.
What are the products of incomplete combustion reaction?
Carbon dioxide, water, carbon monoxide and carbon in the form of soot.