6. (a) Hydrocarbons are widely used as fuels - Leaving Cert Chemistry - Question 6 - 2006
Question 6
6. (a) Hydrocarbons are widely used as fuels.
(i) What are hydrocarbons? Give one major source of hydrocarbons. (8)
(ii) Increasing levels of methane (CH₄) in the... show full transcript
Worked Solution & Example Answer:6. (a) Hydrocarbons are widely used as fuels - Leaving Cert Chemistry - Question 6 - 2006
Step 1
What are hydrocarbons? Give one major source of hydrocarbons.
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Answer
Hydrocarbons are compounds containing only carbon and hydrogen. One major source of hydrocarbons is crude oil, which is a natural resource found in the earth's crust.
Step 2
Increasing levels of methane (CH₄) in the atmosphere are a concern to environmentalists at present. Explain why this is so.
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The increasing levels of methane (CH₄) in the atmosphere are concerning due to its role as a greenhouse gas. Methane is significantly more effective than carbon dioxide at trapping heat in the atmosphere, contributing to global warming. Its rising concentrations lead to enhanced greenhouse effects, resulting in climate change and environmental disruptions.
Step 3
Draw the structure and give the systematic (IUPAC) name of each of the two structural isomers of C₃H₈.
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The two structural isomers of C₃H₈ (propane) are:
Butane (C₄H₁₀):
Structure:
IUPAC Name: Butane.
Isobutane (2-Methylpropane):
Structure:
IUPAC Name: 2-Methylpropane.
Step 4
To purify a sample of benzoic acid, the impure crystals were dissolved in the ___ 1 ___ of hot water.
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minimum
Step 5
The hot solution was filtered to remove the ___ 2 ___ impurities.
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insoluble
Step 6
The filtrate was allowed to cool and, when crystals had formed, they were removed from the solution by filtration, leaving the 3 impurities behind.
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soluble
Step 7
This method of purification of a solid is known as ___ 4 ___.
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recrystallisation
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