Older cars are tested each year to measure the amount of pollutants contained in exhaust fumes - AQA - GCSE Chemistry - Question 7 - 2018 - Paper 2
Question 7
Older cars are tested each year to measure the amount of pollutants contained in exhaust fumes.
Table 4 shows the maximum allowed percentages of exhaust pollutants ... show full transcript
Worked Solution & Example Answer:Older cars are tested each year to measure the amount of pollutants contained in exhaust fumes - AQA - GCSE Chemistry - Question 7 - 2018 - Paper 2
Step 1
Explain how carbon monoxide is produced when petrol is burned in car engines.
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Answer
Carbon monoxide is produced when petrol is burned due to incomplete combustion. This typically occurs when there is an insufficient supply of oxygen during the combustion process, leading to the formation of CO instead of fully oxidized products like carbon dioxide.
Step 2
Suggest two reasons why the maximum allowed percentage of carbon monoxide has been decreased for newer cars.
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Answer
There is greater public concern and awareness regarding the toxic effects of carbon monoxide on health and the environment.
Improved engine technology and the introduction of catalytic converters have contributed to reducing emissions, thereby allowing stricter regulations.
Step 3
Give one reason for having a maximum allowed percentage of unburned hydrocarbons in exhaust fumes.
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Unburned hydrocarbons are regulated to reduce health problems related to air pollution, including respiratory issues and smog formation.
Step 4
Describe how oxides of nitrogen are produced when petrol is burned in car engines.
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Oxides of nitrogen, such as nitrogen dioxide, are produced when nitrogen in the atmosphere reacts with oxygen at high temperatures during combustion. This reaction typically occurs in the presence of a spark from the spark plug.
Step 5
Complete the equation for this reaction. The equation should be balanced.
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2 NO₂ (g) → N₂ (g) + 2 O₂ (g)
Step 6
Give two effects of atmospheric pollution which are reduced by using catalytic converters.
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Reduction of acid rain formation.
Decrease in respiratory problems caused by harmful pollutants in the air.
Step 7
Where in the periodic table are these elements most likely to be found?
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