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 (NOx) are formed in engines primarily through the reaction of nitrogen from the air with oxygen, particularly at high temperatures, such as those found in combustion. The high heat provided by the engine facilitates the combination of nitrogen and oxygen molecules.
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 because they contribute to environmental issues like acid rain and respiratory problems in humans. Reducing these emissions helps to protect both health and the environment.
Step 3
Give the oxidation state of nitrogen in each of NO₂, NH₃ and N₂.
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Answer
The oxidation states of nitrogen are as follows:
In NO₂: +4
In NH₃: -3
In N₂: 0
Step 4
Complete the equation for the reaction between NO₂ and NH₃.
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The balanced equation for the reaction is:
2NO2+4NH3→N2+6H2O
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 than the reactants, typically providing an active surface for the reaction to occur while remaining unchanged at the end of the reaction.
Step 6
Explain why carbon particulates are formed.
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Carbon particulates are formed due to incomplete combustion of fuel, where there is insufficient oxygen in the combustion environment. This leads to the production of soot and carbon particles instead of fully oxidized products like carbon dioxide.
