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
1. Explain how oxides of nitrogen are formed in engines.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Oxides of nitrogen, or NOx, are primarily formed in engines through the reaction of nitrogen and oxygen from the air at high temperatures. During combustion, the extreme heat enables nitrogen molecules in the air to react with oxygen, producing various nitrogen oxides.
Step 2
2. State why it is desirable to decrease emissions of oxides of nitrogen from vehicles.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
It is desirable to decrease emissions of oxides of nitrogen from vehicles to reduce the formation of acid rain and mitigate respiratory problems in humans. High concentrations of NOx can lead to the formation of ground-level ozone, which is harmful to health and the environment.
Step 3
3. Give the oxidation state of nitrogen in each of NO₂, NH₃ and N₂.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
In NO₂, the oxidation state of nitrogen 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.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The balanced equation is:
ightarrow ext{N}_2 + ext{6H}_2 ext{O}$$
Step 5
4. State the meaning of the term heterogeneous catalyst.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
A heterogeneous catalyst is a catalyst that exists in a different phase (state) from the reactants. In other words, it usually exists in solid form while the reactants are in gas or liquid form, facilitating the reaction without being consumed in the process.
Step 6
5. Explain why carbon particulates are formed.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Carbon particulates are formed due to incomplete combustion of fossil fuels in both diesel and petrol engines. When there is insufficient oxygen to completely oxidize the fuel, solid carbon particles are produced as a byproduct.
