Organic chemistry - crude oil, hydrocarbon properties, alkanes, fractional distillation, combustion Flashcards
Describe how crude oil is formed
Crude oil is a finite resource (if we continue using it then crude oil will one day run out) found in rocks.
Crude oil is formed over millions of years from the remains of an ancient biomass consisting mainly of plankton that was buried in mud
where is crude oil found
crude oil is found in rocks
what type of resource is crude oil
crude oil is a finite resource
what is an energy resource
An energy resource is anything that we use to obtain energy
what is a renewable resource
A renewable energy resource is one that can be replenished as it is being used and therefore will not run out
what is a finite resource
A non-renewable energy resource is one that cannot be replenished in a short enough time period and therefore will run out
Crude oil is a mixture of molecules called ________
hydrocarbons
Crude oil is a mixture of a very large number of compounds. Most of
the compounds in crude oil are hydrocarbons
describe structure of methane
contains one carbon atom covalently bonded to four hydrogen atoms
Describe what is meant by a hydrocarbon
Hydrocarbons are molecules made up of hydrogen and carbon atoms only
General formula of alkanes
Alkanes have the general formula CnH2n+2
name first four alkanes, state their molecular formulas and draw their their displayed formulas, and their structural formulas
Methane - 1 CH4
Ethane - 2 C2H6
Propane -3 C3H8
Butane -4 C4H10
displayed = h-c-h etc.
structural - groups of atoms ch3ch3 for ethane
https://bam.files.bbci.co.uk/bam/live/content/zskfk2p/medium
Explain why alkanes are said to be saturated molecules
Alkanes are saturated molecules
That is because the carbon atoms are fully bonded to hydrogen atoms
Describe what is meant by an alkane
a saturated hydrocarbon with the general formula CnH2n+2
properties of hydrocarbons
Viscosity
Flammability
Boiling point
properties of short chain hydrocarbons
low viscosity
highly flammable
low boiling point
properties of long chain hydrocarbons
high Viscosity
low Flammability
high Boiling point
What is viscosity
Viscosity tells us the thickness of a fluid
Fluids with a high viscosity flow slowly
Describe how viscosity of hydrocarbons depend on the size of their molecules
As the size of the hydrocarbon molecule increases, the molecules get more viscous
Very long chain hydrocarbons flow very slowly
Long chain hydrocarbons are extremely viscous
What is flammability
Flammability tells us how easily a hydrocarbon combusts (burns)
Describe how flammability of hydrocarbons depend on the size of their molecules
As the size of the hydrocarbon molecule increases, the molecules get less flammable
Short chain hydrocarbons are extremely flammable
Long chain hydrocarbons are very difficult to burn
What is the boiling point
The boiling point is the temperature at which a liquid turns to a gas
Describe how the boiling point of hydrocarbons depend on the size of their molecules
As the size of the hydrocarbon molecule increases, the boiling point also increases.
Short chain hydrocarbons have low boiling points
(first four alkanes are gases at room temperature)
Very long chain hydrocarbons have very high boiling points
The first four alkanes are gases at room temperature
What does this tell us about their boiling point
Short chain hydrocarbons have low boiling points
(first four alkanes are gases at room temperature)
this is because they all have boiling points which are lower than room temperature
Describe how hydrocarbons can be used as fuels
Hydrocarbon fuels release energy when combusted (burned)
HYDROCARBONS ARE USED AS FUELS DUE TO THE AMOUNT OF ENERGY RELEASED WHEN THEY COMBUST COMPLETELY
LOTS OF ENERGY
ships, planes and cars all run on____________
hydrocarbon fuels
What happens to hydrocarbon fuels when they combust (burn)
Hydrocarbon fuels release energy when combusted (burned)
Describe what happens during combustion of a hydrocarbon fuel
During combustion, the carbon and hydrogen atoms in the (hydrocarbon) fuel react with oxygen.
The carbon and hydrogen are oxidised
During the combustion of a hydrocarbon fuel if the oxygen is unlimited what is produced
During the combustion of a hydrocarbon fuel if the oxygen is unlimited, this reaction produces carbon dioxide and water. This is called complete combustion
What does the complete combustion of a hydrocarbon produce
The complete combustion of a hydrocarbon produces carbon dioxide
and water
what is complete combustion of a hydrocarbon fuel
During combustion, the carbon and hydrogen atoms in the (hydrocarbon) fuel react with oxygen.
The carbon and hydrogen are fully oxidised - and the products/produces co2 + water
Write balanced equations for the complete combustion of methane
methane + oxygen -> carbon dioxide + water
CH4 + 2O2 —-> CO2 + 2H2O
Describe how the hydrocarbons in crude oil can be separated by fractional distillation
Firstly, the crude oil is heated to a very high temperature
This causes the crude oil to boil. All of the hydrocarbons evaporate and turn into a gas
The crude oil vapour is now fed into the fractional distillation column
The column is hotter at the bottom and cooler at the top
The hydrocarbon vapours now rise up the column
Hydrocarbons condense (turn back to a liquid) when they reach their boiling point
The liquid fractions are then removed
The remaining hydrocarbons continue moving up the column
These now condense when they reach their boiling points
Very long chain hydrocarbons have very high boiling points
These hydrocarbons are removed from the bottom of the column
Very short chain hydrocarbons have low boiling points
These do not condense
They are removed from the top of the column as gases
State the functions of the important fractions
The fractions can be processed to produce fuels and feedstock for the petrochemical industry.
Some fractions are used as fuels.
E.G. Petrol and diesel are used to fuel cars
kerosene is used as jet fuel
heavy fuel oil is used to power ships
liquified petroleum gas is used in camping stoves
Some fractions are used as feedstock for the petrochemical industry
A feedstock is a chemical that is used to make other chemicals
Feedstock fractions are used to make solvents, lubricants, detergents, polymers
each hydrocarbon has a different
boiling point
difference in boiling point between longer chain hydrocarbons and shorter chain hydrocarbons
Longer chain hydrocarbons have a higher boiling point than shorter chains
What must be done in order for the hydrocarbons in crude oil to be useful
In order for the hydrocarbons in crude oil to be useful, we have to separate them
The name of the technique used to separate hydrocarbons in crude oil
In order for the hydrocarbons in crude oil to be useful, we have to separate them
To do that, we use a technique called fractional distillation
In fractional distillation what is the crude oil separated into
In fractional distillation, crude oil is separated into fractions
What are fractions
What do fractions contain
Fractions contain hydrocarbons with a similar number of carbon atoms
Where are long chain hydrocarbons removed and why
Very long chain hydrocarbons have very high boiling points
These hydrocarbons are removed from the bottom of the column
Where are short chain hydrocarbons removed, why, and in what state and why
Very short chain hydrocarbons have low boiling points
These do not condense
They are removed from the top of the column as gases
What does fractional distillation produce
Fractional distillation produces fractions
