This question is about emissions of oxides of nitrogen from petrol and diesel engines - AQA - A-Level Chemistry - Question 1 - 2020 - Paper 3
Question 1
This question is about emissions of oxides of nitrogen from petrol and diesel engines.
1. Explain how oxides of nitrogen are formed in engines.
2. State why it is ... show full transcript
Worked Solution & Example Answer:This question is about emissions of oxides of nitrogen from petrol and diesel engines - AQA - A-Level Chemistry - Question 1 - 2020 - Paper 3
Step 1
Explain how oxides of nitrogen are formed in engines.
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Answer
Oxides of nitrogen are formed in engines primarily through the reaction of nitrogen and oxygen from the air at high temperatures. When fuel is burned in the combustion engine, the high temperatures enable nitrogen from the air to react with oxygen, producing nitrogen oxides (NOx).
Step 2
State why it is desirable to decrease emissions of oxides of nitrogen from vehicles.
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It is desirable to decrease emissions of oxides of nitrogen from vehicles to prevent the formation of acid rain, which can cause environmental and respiratory problems. High levels of NOx contribute to air pollution, which is harmful to human health.
Step 3
Give the oxidation state of nitrogen in each of NO2, NH3 and N2;
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The oxidation state of nitrogen in NO2 is +4, in NH3 is -3, and in N2 is 0.
Step 4
Complete the equation for the reaction between NO2 and NH3.
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The equation for the reaction is:
ightarrow ext{N}_2 + ext{3H}_2 ext{O}$$
Step 5
State the meaning of the term heterogeneous catalyst.
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A heterogeneous catalyst is a catalyst that exists in a different phase (solid, liquid, or gas) from the reactants. It facilitates the reaction without being consumed in the process, allowing the products to form while remaining unchanged.
Step 6
Explain why carbon particulates are formed.
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Carbon particulates are formed in both diesel and petrol vehicles due to incomplete combustion of the fuel. When there is insufficient oxygen during the combustion process, solid carbon particles are released as a byproduct.
