Alkenes
(a) The table shows information about two alkenes - Edexcel - GCSE Chemistry - Question 4 - 2013 - Paper 1
Question 4
Alkenes
(a) The table shows information about two alkenes. Complete the table to show the names and structures of these alkenes.
| name | structure of a molecule... show full transcript
Worked Solution & Example Answer:Alkenes
(a) The table shows information about two alkenes - Edexcel - GCSE Chemistry - Question 4 - 2013 - Paper 1
Step 1
Complete the table to show the names and structures of these alkenes.
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Answer
The structure of ethene is represented as:
H H
\ /
C = C
/ \
H H
The name of the alkene is ethene.
Step 2
State what is meant by unsaturated.
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Answer
An unsaturated compound contains a double bond, which means it has multiple bonds between carbon atoms. This distinguishes it from saturated compounds, which only have single bonds.
Step 3
Describe what is seen when ethene is passed into bromine water.
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Answer
When ethene is passed into bromine water, the color of the bromine solution changes from orange to colorless. This indicates that a reaction has occurred, as the ethene reacts with the bromine.
Step 4
Explain what is meant by cracking.
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Answer
Cracking is the process of breaking down large hydrocarbon molecules into smaller molecules, such as alkenes or alkane chains. This is typically done using heat or catalysts to decompose longer-chain hydrocarbons, resulting in more useful products.
Step 5
Complete the sentence by putting a cross ✗ in the box next to your answer.
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Answer
The correct answer is D - polymerisation. Molecules of ethene join together to form poly(ethene) through a polymerisation process.
Step 6
Explain why the presence of waste plastic in landfill sites causes problems.
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Answer
Waste plastic in landfill sites is problematic because it does not decompose easily, leading to long-term pollution. Additionally, it can harm wildlife and contaminate soil and water sources. Its persistence in the environment poses significant ecological challenges.
