This question is about the ozone layer in the upper atmosphere - AQA - A-Level Chemistry - Question 9 - 2021 - Paper 2
Question 9
This question is about the ozone layer in the upper atmosphere.
1. State why the ozone layer is beneficial for living organisms.
---
2. State how chlorofluorocarb... show full transcript
Worked Solution & Example Answer:This question is about the ozone layer in the upper atmosphere - AQA - A-Level Chemistry - Question 9 - 2021 - Paper 2
Step 1
State why the ozone layer is beneficial for living organisms.
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
The ozone layer absorbs harmful ultraviolet (UV) radiation from the sun, thereby preventing skin cancer and protecting ecosystems.
Step 2
State how chlorofluorocarbons (CFCs) form chlorine atoms in the upper atmosphere.
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
Chlorofluorocarbons (CFCs) undergo photodissociation in the upper atmosphere, breaking down into chlorine atoms.
Step 3
Give equations to show how chlorine atoms catalyse the decomposition of ozone.
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
Cl• + O3 → ClO• + O2
ClO• + O → Cl• + O2
The chlorine atom acts as a catalyst, being regenerated in the process.
Step 4
Complete each step in the mechanism.
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
Cl• + CHF3 → CHF2Cl + H•
CHF2Cl → CHF3 + Cl•
The type of step shown by both equations is 'Propagation'.
