Stratospheric Ozone and Depletion Flashcards

This set explores the importance of stratospheric ozone, the mechanism of depletion by CFCs and natural processes, and the global efforts to reduce ozone depletion.

What are the primary dangers of $UV-B$ and $UV-C$ radiation to life on land without the ozone layer?

Cancer and tissue damage.

What are the health benefits of the stratospheric ozone layer?

Prevention of skin cancer and cataracts.

How is tropospheric ozone characterized and what are its effects?

It is a respiratory irritant that damages plant tissue and contributes to smog.

What anthropogenic chemicals are responsible for the breakdown of stratospheric $O_3$?

Chlorofluorocarbons (CFCs).

What were the common uses for Chlorofluorocarbons (CFCs)?

They were used as refrigerant chemicals and in aerosol cans.

What event initiates the separation of a free chlorine ($Cl$) atom from a CFC molecule?

$UV$ radiation.

Why does a free chlorine ($Cl$) atom bond to an oxygen atom in the stratosphere?

Because $Cl$ has a high electronegativity, it bonds to an $O$ atom from $O_3$ and converts it to $O_2$.

What conditions lead to natural ozone depletion in Antarctica?

The Antarctica spring melt, which forms polar stratospheric clouds.

What are polar stratospheric clouds composed of?

$H_2O_{(g)}$ and $HNO_3$ (nitric acid).

Which two substances react to release free chlorine ($Cl$) during natural depletion processes?

$ClNO_2$ (chlorine nitrate) and $HCl$ react to give off free $Cl$, which are then photolyzed.

What was the purpose of the Montreal Protocol of '87?

A global agreement to phase out CFCs in refrigerants, aerosols, and other products.

Why are HCFCs not a permanent solution for ozone protection?

They are greenhouse gases (GHG) that still deplete ozone, although to a lesser extent than CFCs.

How is ozone ($O_3$) formed in the stratosphere?

When a free oxygen atom from a reaction combines with an $O_2$ molecule.

What specific types of radiation are absorbed by the cycle of ozone formation and breakdown?

All $UV-C$ radiation and much of the $UV-B$ radiation.

What is the result when $UV-C$ breaks down ozone ($O_3$)?

It breaks into $O_2$ and $O$, which can then bond with another free $O$ to form $O_2$.