Crude oil is a complex mixture consisting mainly of hydrocarbons - Leaving Cert Chemistry - Question 6 - 2012
Question 6
Crude oil is a complex mixture consisting mainly of hydrocarbons. It is fractionally distilled in oil refineries to produce a wide range of useful materials.
(a) Wh... show full transcript
Worked Solution & Example Answer:Crude oil is a complex mixture consisting mainly of hydrocarbons - Leaving Cert Chemistry - Question 6 - 2012
Step 1
What are hydrocarbons?
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Answer
Hydrocarbons are organic compounds that consist exclusively of carbon and hydrogen atoms. They are the primary constituents of crude oil and serve as the foundational building blocks for a large variety of fuels and chemicals.
Step 2
Name any two of the fractions obtained by the fractional distillation of crude oil in an oil refinery.
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Answer
Gasoline (petrol)
Kerosene
Step 3
Give one use of each fraction you have named.
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Answer
Gasoline: Used primarily as fuel for vehicles.
Kerosene: Commonly used as a fuel for heating and jet engines.
Step 4
What are the octane numbers of these reference hydrocarbons?
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Write the structural formula of either one of the reference hydrocarbons.
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Answer
The structural formula of heptane is:
CH3-CH2-CH2-CH2-CH2-CH2-CH3
Or the structural formula of 2,2,4-trimethylpentane is:
CH3
|
CH3 - C - CH - CH2 - CH3
|
CH3
Step 6
State one way in which the octane number of a fuel can be increased.
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One way to increase the octane number of a fuel is to add anti-knock agents such as tetraethyl lead or to reformulate the fuel through processes like isomerization or cracking, which create higher octane components.
Step 7
Draw the structural formula of benzene.
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Answer
The structural formula of benzene is:
C6H6
________
/ \
| |
\________/
Alternatively, it can be represented as a hexagon with a circle inside, indicating resonance among the bonds.
Step 8
What health concern is associated with the presence of benzene in fuels?
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Benzene is known to be a carcinogenic substance, meaning it has the potential to cause cancer in humans upon prolonged exposure.
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