Organic chemistry
Crude oil is a mixture of different lengths of hydrocarbons. It was formed by the dead
remains of marine organisms, mainly plankton, which settled at the bottom of the ocean
floor and buried with sediment over millions of years. They changed due to high
temperatures and pressure to make hydrocarbons.
Hydrocarbons are compounds that contain only hydrogen and carbon e.g. alkanes. They
are used for: fuels, solvents, lubricants, detergents, and polymers.
Crude oil can be separated by the process of fractional distillation: vaporized crude oil is
out into a fractioning column which is hot at the bottom and cooler at the top. Different
lengths of hydrocarbons condense at different fractions due to different boiling points:
- Short chain hydrocarbons condense at the top because they have smaller boiling
points due to less intermolecular forces, so less energy is required to overcome
them. Short chain hydrocarbons have low viscosity, high flammability, and are
cleaner when burnt (uses include petroleum gas for fuel).
- Long chain hydrocarbons condense at the bottom of the tower because they have
larger boiling points due to having more intermolecular forces that require more
energy to overcome. They have high viscosity, low flammability, and they burn with
a dark flame and may produce soot. (Uses include bitumen for asphalt)
, Alkanes are hydrocarbons with the functional group C-C (single carbon bond) - saturated.
They have the general formula CnH2n+2. The first four alkanes are:
Long chain alkanes are not useful therefore they are broken down into shorter chain
alkanes so they can be used as fuels which are high in demand. This is done by cracking
which produces shorter chain alkanes and an alkene.
- Catalytic cracking breaks down long chain alkanes into short chain alkanes and
alkenes with the use of a catalyst and high temperature.
- Steam cracking breaks down long chain alkanes into short chain alkanes and
alkenes by vaporizing them and passing them over steam at high temperature.
Alkenes are another form of hydrocarbons with a functional group of C=C (carbon double
bond) - unsaturated. They have the general formula CnH2n. The first four alkenes are:
Alkenes can be distinguished from alkanes by adding bromine water to each of them.
Alkanes will leave the solution orange, while alkenes will turn the solution from orange to
colorless as they are unsaturated – the double bond is broken so bromine can bond to it.
This is an example of an addition reaction.
Other addition reactions include:
Crude oil is a mixture of different lengths of hydrocarbons. It was formed by the dead
remains of marine organisms, mainly plankton, which settled at the bottom of the ocean
floor and buried with sediment over millions of years. They changed due to high
temperatures and pressure to make hydrocarbons.
Hydrocarbons are compounds that contain only hydrogen and carbon e.g. alkanes. They
are used for: fuels, solvents, lubricants, detergents, and polymers.
Crude oil can be separated by the process of fractional distillation: vaporized crude oil is
out into a fractioning column which is hot at the bottom and cooler at the top. Different
lengths of hydrocarbons condense at different fractions due to different boiling points:
- Short chain hydrocarbons condense at the top because they have smaller boiling
points due to less intermolecular forces, so less energy is required to overcome
them. Short chain hydrocarbons have low viscosity, high flammability, and are
cleaner when burnt (uses include petroleum gas for fuel).
- Long chain hydrocarbons condense at the bottom of the tower because they have
larger boiling points due to having more intermolecular forces that require more
energy to overcome. They have high viscosity, low flammability, and they burn with
a dark flame and may produce soot. (Uses include bitumen for asphalt)
, Alkanes are hydrocarbons with the functional group C-C (single carbon bond) - saturated.
They have the general formula CnH2n+2. The first four alkanes are:
Long chain alkanes are not useful therefore they are broken down into shorter chain
alkanes so they can be used as fuels which are high in demand. This is done by cracking
which produces shorter chain alkanes and an alkene.
- Catalytic cracking breaks down long chain alkanes into short chain alkanes and
alkenes with the use of a catalyst and high temperature.
- Steam cracking breaks down long chain alkanes into short chain alkanes and
alkenes by vaporizing them and passing them over steam at high temperature.
Alkenes are another form of hydrocarbons with a functional group of C=C (carbon double
bond) - unsaturated. They have the general formula CnH2n. The first four alkenes are:
Alkenes can be distinguished from alkanes by adding bromine water to each of them.
Alkanes will leave the solution orange, while alkenes will turn the solution from orange to
colorless as they are unsaturated – the double bond is broken so bromine can bond to it.
This is an example of an addition reaction.
Other addition reactions include:
