This question is about hydrocarbons - AQA - GCSE Chemistry - Question 2 - 2016 - Paper 1
Question 2
This question is about hydrocarbons.
Most of the hydrocarbons in crude oil are alkanes.
Large alkane molecules can be cracked to produce more useful molecules.
Th... show full transcript
Worked Solution & Example Answer:This question is about hydrocarbons - AQA - GCSE Chemistry - Question 2 - 2016 - Paper 1
Step 1
Give two conditions used to crack large alkane molecules.
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Answer
High temperature (around 250-900 °C)
Use of a catalyst, such as zeolite or alumina.
Step 2
Complete the sentence.
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Answer
When alkenes react with bromine water the colour changes from orange to colourless.
Step 3
Complete the displayed structure of butane.
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The displayed structure of butane is:
H H
| |
H--C--C--H
| |
H H
Step 4
Calculate the energy released by 1.0 g of decane in kJ.
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Energy released = 20.30 kJ.
Step 5
Suggest one improvement to the apparatus, or the use of the apparatus, that would make the temperature increase of the water for each fuel more accurate.
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One improvement would be to use a lid on the beaker to reduce heat loss.
Step 6
Give a reason why this is an improvement.
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This is an improvement because it will insulate the beaker, ensuring less heat is lost to the environment.
Step 7
Name this black substance.
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The black substance is carbon or soot.
Step 8
Suggest why it is produced.
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It is produced due to incomplete combustion of the fuels.
Step 9
Give two reasons why the results in Table 1 support this conclusion.
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Hexane has the highest energy released per gram, indicating it is the most efficient fuel.
Hexane produces less smoke, suggesting cleaner combustion compared to the other fuels.
Step 10
Describe the advantages and disadvantages of using hydrogen instead of petrol in car engines.
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Advantages of using hydrogen:
Hydrogen only produces water upon combustion, leading to zero pollution and contributing less to global warming.
Combustion of hydrogen does not produce sulfur dioxide, reducing acid rain risk.
Disadvantages of using hydrogen:
Hydrogen is a gas at room temperature making it difficult to store and transport.
Production of hydrogen often relies on fossil fuels, which contributes to environmental issues.
