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Use chemical equations to show how ozone is depleted in the stratosphere - HSC - SSCE Chemistry - Question 22 - 2011 - Paper 1
Question 22
Use chemical equations to show how ozone is depleted in the stratosphere. Outline ONE method used to monitor stratospheric ozone.
Worked Solution & Example Answer:Use chemical equations to show how ozone is depleted in the stratosphere - HSC - SSCE Chemistry - Question 22 - 2011 - Paper 1
Step 1
Use chemical equations to show how ozone is depleted in the stratosphere.
Answer
Ozone ( ext{O}_3) in the stratosphere is primarily depleted by chemical reactions involving chlorine species, which are derived from chlorofluorocarbons (CFCs). The overall reaction can be illustrated as follows:
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Initiation:
CFCs are broken down by ultraviolet (UV) radiation:
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Propagation:
The free chlorine atom reacts with ozone:
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Termination:
The chlorine monoxide (ClO) can then react with a free oxygen atom:
This cycle results in the depletion of ozone in the stratosphere, as chlorine catalysts can continue to repeat this process, leading to significant ozone loss.
Step 2
Outline ONE method used to monitor stratospheric ozone.
Answer
One method used to monitor stratospheric ozone is ground-based spectroscopy. This technique involves the use of spectrometers that measure the intensity of sunlight as it passes through the atmosphere. By analyzing the absorption features in the UV spectrum, scientists can determine the concentration of ozone at different altitudes. This method provides continuous data on ozone levels, helping to track changes over time.