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 primarily formed in engines through the reaction between nitrogen and oxygen in the air at high temperatures. This occurs during the combustion process when the engine operates, leading to the formation of nitrogen oxides such as NO and NO2.
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 reduce the formation of acid rain and combat respiratory problems. High levels of nitrogen oxides can contribute to smog formation and are 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 it is -3, and in N2 it is 0.
Step 4
Complete the equation for the reaction between NO2 and NH3.
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The balanced equation for the reaction is:
ightarrow ext{N}_2 + ext{2H}_2 ext{O}$$
Step 5
State the meaning of the term heterogeneous catalyst.
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A heterogeneous catalyst is a catalyst that is in a different phase from the reactants. This means that the catalyst is typically solid while the reactants are in gas or liquid form, facilitating the reaction at the interface between the phases.
Step 6
Explain why carbon particulates are formed.
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Carbon particulates are formed due to incomplete combustion of hydrocarbon fuels in both diesel and petrol vehicles. When there is not enough oxygen for complete combustion, solid carbon particles are produced as a byproduct.
