Have you ever wondering what is the composition of
petroleum?
·
It comprises of alkanes, cycloalkanes,
aromatic hydrocarbons, and complex chemicals like asphaltenes.
·
Each petroleum variety has a unique mix of
molecules to determine its physical and chemical properties.
1)
alkane
So, let’s talk about the alkanes in
petroleum. As everyone know alkanes are saturated hydrocarbons with contain
only carbon and hydrogen. Besides, they can existed in the form of branched or
straight chain. So, the general formula for them are CnH2n+2.
Besides, they can have 1 to 40 carbon atoms per molecule.
- ·
Pentane (C5H12)
to octane (C8H18) are normally refined into gasoline.
- · Nonane (C9H20) to hexadecane (C16H34) can be refined into diesel fuel, kerosene or jet fuel.
- · Alkanes that have more than 16 carbon atoms can refined into fuel oil and lubricating oil.
- ·
Paraffin wax is an alkane
with approximately 25 carbon atoms and normally used in candles and in crayons.
- · Those alkane with four or fewer carbon atoms are known as petroleum gases.
Do
you know?
The
petroleum gases are sold as liquefied petroleum gas inside the gas tank after
being pressurize. During the winter season, butane gas (C4H10),
is blended into the gasoline pool. So, it is best known for powering cigarette
lighters. Besides, it is also a main fuel source for many developing countries.
2)
Cycloalkanes
Cycloalkanes is similar to
alkane which contain only carbon-hydrogen bonds. But, the carbon atoms are
joined up in the form of ring.
The cycloalkanes in petroleum also known as
naphthenes. So, they are saturated hydrocarbons with the formula CnH2n.
Cycloalkanes have similar properties to alkanes but they have higher boiling
points. The residue of the refinery process is known as asphalt.
1)
Aromatic
hydrocarbons
The aromatic hydrocarbons are unsaturated
hydrocarbons with minimum one planar six-carbon rings also known as benzene
rings. Therefore, the hydrogen atoms are attached with the formula CnHn.
They are flammable and tend to burn with a sooty flame. Majority of them have a
sweet aroma. However, some of them are carcinogenic and could cause lung cancer
after inhaled.
Facts:
All these different chemical molecules are
separated by fractional distillation at the petroleum industry to produce
gasoline, jet fuel, kerosene, and other hydrocarbons. For example, 2,2,4-trimethylpentane
is widely used in gasoline. It has a chemical
formula of C8H18 and reacts with oxygen exothermically. The
reaction is shown below.
2
C8H18(l) + 25 O2(g) → 16 CO2(g) +
18 H2O(g) (ΔH =
−5.51 MJ/mol of octane)
Besides, the different molecules in an oil
sample can be examine in the laboratory. The molecules are separated in a gas
chromatograph after extracted in a solvent. Finally, the scientists will
determine with a suitable detector such as a flame ionization detector or a
mass spectrometer.
Furthermore, the incomplete combustion of petroleum
or gasoline will produce toxic byproducts. When the combustion process is
deprived of oxygen will results in the production of carbon monoxide. In
addition, the combustion of gasoline would produce exhaust gases and given out
from the car engine. The exhaust gases usually include nitrogen oxides which
would lead to photochemical smog due to the high temperatures and high
pressures involved.
Useful Links: 1) http://www.chemguide.co.uk/organicprops/alkanes/background.html
2) http://www.petroleum.co.uk/alkane-chemistry
3) http://www.shell.com/global/future-energy/natural-gas.html
4) https://www.khanacademy.org/science/organic-chemistry/bond-line- structures-alkanes-cycloalkanes
5) http://www.eia.gov/energyexplained/index.cfm?page=oil_home
Authors : Aaron Leong Hee Lee, Huong Nai Zheng, Ong Kai Yin, Lim Huang Xu
Authors : Aaron Leong Hee Lee, Huong Nai Zheng, Ong Kai Yin, Lim Huang Xu
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