Organic chemistry Flashcards
Explain separating crude oil (3)
1) Heat crude oil so it turns into vapour
2) Vapour eneters fractionating column that has a temperature gradient
3) Fractions condense at different levels because they have different boiling points
Crude oil
Is a mixture of hydrocarbons with different carbon chain lengths
Hydrocarbons
Molecules made up only of carbon and hydrogen atoms
List properties of hydrocarbons change with molecular size
1) Intermolecular attraction forces increase
2) Boiling point increases
3) Liquids become less volatile
4) Liquids become viscus
5) Less flammable
less Volatile
A liquid evaporates less quickly
more Viscus
Liquids take longer to flow , like syrup
How can crude oil be separated? Why?
Fractional distillation, as crude oil is a mixture of different hydrocarbons they have different boiling points
Fraction
A group of hydrocarbons with similar boiling points
What happens to gas molecules during fractional distillation
Condensed back into liquid in the condenser
List all the fractions of crude oil starting with lowest boiling point (7)
1) Refinery gasses
2) Gasoline (petrol)
3) Naphtha
4) Kerosine
5) Diesel oil (gas oil)
6) Fuel oil
7) Bitumen
Usage of Refinery gasses
Bottled gas
Usage of Gasoline (petrol)
Fuel for cars
Usage of Naphtha
Making chemicals
Usage of Kerosine
Aircraft fuel
Usage of Diesel oil
Fuel for cars, lorries, buses
Usage of Fuel oil
Fuel for ships, power stations
Usage of Bitumen
Roads
List factors which are different in small hydrocarbons to large (4)
1) Low boiling point
2) Very volatile
3) Flow easily
4) Ignite easily
Why does viscosity change?
More bonds, bigger mass, the forces of attraction between the molecules increases. More force is required to break the bonds
Why does flammability change?
More bonds, more energy to break the bonds as there are more forces of attraction between the molecules
Alkanes
Saturated hydrocarbon molecule
Saturated
An organic compound in which all the bonds are single bonds
What is the generic formula of alkanes
CnH2n+2
List factors of alkanes (2)
1) All have similar structure
2) They have CH3 at each end of the molecule
What is the difference between alkanes
Number of CH2 groups between the two ends