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 from the incomplete combustion of petrol. This occurs when there is an insufficient or limited supply of oxygen in the engine, resulting in carbon atoms combining with only one oxygen atom instead of two, leading to the formation of carbon monoxide.
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 a greater public concern and awareness regarding air pollution and its effects on health.
Improved engine technology has been developed, leading to more efficient combustion processes that reduce carbon monoxide emissions.
Step 3
Give one reason for having a maximum allowed percentage of unburned hydrocarbons in exhaust fumes.
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To reduce harmful health problems that may arise from exposure to unburned hydrocarbons, such as respiratory issues.
Step 4
Describe how oxides of nitrogen are produced when petrol is burned in car engines.
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Answer
Oxides of nitrogen are produced when nitrogen from the atmosphere reacts with oxygen during high-temperature combustion in the engine. This typically occurs at the high temperatures generated by the engine, which allows nitrogen and oxygen molecules to combine.
Step 5
Complete the equation for this reaction. The equation should be balanced.
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The balanced equation is:
2 NO₂ (g) → N₂ (g) + O₂ (g)
Step 6
Give two effects of atmospheric pollution which are reduced by using catalytic converters.
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Answer
Catalytic converters help reduce respiratory problems caused by harmful pollutants in the air.
They also reduce the formation of acid rain, which can harm ecosystems and structures.
Step 7
Where in the periodic table are these elements most likely to be found?
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The elements in catalytic converters are most likely to be found in the transition metals section of the periodic table.
