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.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
High temperature (around 250-900 °C)
Presence of a catalyst, such as zeolite or steam.
Step 2
When alkenes react with bromine water the colour changes from orange to __________.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
colourless.
Step 3
Complete the displayed structure of butane.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The structure of butane is:
H H H
| | |
H—C—C—C—C—H
| | |
H H H
Step 4
Calculate the energy released by 1.0 g of decane in kJ.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The energy released by 1.0 g of decane is 16.80 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.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Use a lid to insulate the beaker and reduce heat loss.
Step 6
Name this black substance.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Carbon soot.
Step 7
Suggest why it is produced.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
It is produced due to incomplete combustion of the fuels.
Step 8
Give two reasons why the results in Table 1 support this conclusion.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Hexane has the highest energy released per gram, showing it is more efficient as a fuel.
Hexane produces the least smoke, indicating it burns cleaner, thereby being better for the environment.
Step 9
Describe the advantages and disadvantages of using hydrogen instead of petrol in car engines.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Advantages of Using Hydrogen:
Hydrogen combustion only produces water, causing no pollution.
Hydrogen does not produce carbon dioxide or contribute to global warming.
Hydrogen is more efficient in energy release compared to petrol.
Disadvantages of Using Hydrogen:
Hydrogen is difficult to store or transfer as it escapes easily.
Most hydrogen is derived from fossil fuels, which raises environmental concerns.
Infrastructure for hydrogen refueling is limited and requires significant development.
