Chemistry -Ozone Layer Flashcards
What is ozone?
An atmospheric component found in the stratosphere being about 1ppm
What is the function of ozone?
Deflection of harmful UV light
What wavelength does ozone absorb?
300nm
What is 300nm harmful?
It can damage DNA
What are CFC;s?
1-2 carbon compounds containing a Cl and F , both nontoxic and stable.
Halons
Unreactive gas moecules of carbon with bromine and other halogens
What is the function of halons in the atmosphere?
Sequester H atoms that otherwise sustain combustsion reactions, by their atomic bromine
What happens to CFC in the ozone layer?
Photodecompostion by high UV radiation light, breaking the C-Cl bonds, with chlorine release
Stoichiochemistry of CFC breakdown?
Cl2CF2 + hV —> Cl + ClCF2
What is the negative effect of the stability of CFC?
Long atmospheric lifetime and undergo no degradation in the troposphere, rising to high as stratosphere
What do ClO radicals do in the stratosphere?
Dimerse for further UV breakdown with free chlorine release
What does chlorine do when formed in the stratosphere?
Degrades ozone
What happens do chlorine dioxide in the stratosphere?
Broken down by UV light, releasing diatomic oxygen and chlorine
What is the threshold of ozone?
220 Dalton uniits
What is the threshold of ozone based on?
The fact no lower measurment have been observed before 1979
When is the ozone hole formed?
Antartica at summer times.
What happens to the closed ozone hole during the inwter?
Polar vortexes are induced due to so sunlight.
What are polar vortexes composed of?
Molecules like HNO3, H2SO4, H2O, and HCl
What is polar vortex HCl generated by?
CFC photochemical disassociation followed by hydrogen abstraction from methane
What happens during spring when sunlight returns to antartic?
Chlroine can be generated from with Hcl forming photochemically reactive Cl2/HOCL
How is ozone formed?
Dissassociation of O2 into elemental oxygen, each reacting with molecular oxygen to form ozone.
Why is the ozone layer so thin?
Because the molecules beneath the ozone layer contain no UV light that can break O2 into O, due to its absorption by the ozone layer.
Why is there no ozone above the ozone layer?
Oxygen disassoicated into O has very little molecular oxygen to combine/produce O3.
What does ozone absorption result in?
Heat generation.
Why does UV-B cause human damage?
Instability of cell divsion translation
