6.2 Stratospheric Ozone

Question 1

Location of the ozone layer

Answer 1

Stratosphere,
Between 15 and 35km up.

Question 2

Function of the ozone layer

Answer 2

Absorption of UV radiation (particularly dangerous short wave length UVB and UVC).
Don’t say “reflection”.

Question 3

Negative effect of excess UV radiation on organisms.

Answer 3

sunburn, skin cancer, cataracts, and DNA damage in living organisms, including plants and phytoplankton.

Question 4

Why at least some UV exposure is important to humans

Answer 4

stimulates production of vitamin D in the skin, which is essential for bone health, immune function, and overall well-being.
Also helps regulate circadian rhythms and mood.

Question 5

Oxygen radical

Answer 5

An oxygen radical is a highly reactive oxygen atom (O) that can initiate or participate in various chemical reactions, including ozone formation.

Radicals are formed when O2 molecules are split apart by high energy UV rays.

Question 6

Diatomic gas

Answer 6

Stable form of gases such as oxygen, nitrogen, hydrogen and chlorine in which two atoms are covalently bonded together to achieve a full outer shell of electrons.
Notated with a “2” subscript

Question 7

How is ozone formed int he atmosphere?

Answer 7

Ozone is formed when UV light splits oxygen molecules (O₂) into oxygen radicals, which then bond with other oxygen molecules to create ozone (O₃).

Question 8

Sources of CFC in the atmosphere

Answer 8

CFCs are released into the atmosphere from products like refrigeration systems, air conditioners, and aerosol propellants.

Question 9

What does CFC stand for

Answer 9

chloroflurocarbon
An acronym, like DNA (not a chemical formula)

Question 10

Compare CFCs and HFCs

Answer 10

• CFCs deplete ozone. HFCs do not.
• HFCs are worse greenhouse gases than CFCs (higher GWP)
• CFCs last longer in the atmosphere (are more persistent) than HFCs.

Question 11

How do CFCs deplete ozone?

Answer 11

CFCs release chlorine atoms which catalyze the breakdown of ozone molecules.
The chlorine atoms “recycle” and this one chlorine atom can be responsible for the breakdown of many ozone molecules.

Question 12

Montreal Protocol

Answer 12

A global treaty signed in 1987 aimed at phasing out the production and use of ozone-depleting substances.

Question 13

Hole in the ozone layer

Answer 13

The significant thinning of the ozone layer over Antarctica, primarily caused by CFCs.
Discovered in 1985 Got bigger until the early 2000s, then started closing.

Question 14

Why is the hole in the ozone layer over Antarctica?

Answer 14

the region’s unique atmospheric conditions, including the polar vortex and extremely cold temperatures.

Question 15

Significance of the Montreal Protocol

Answer 15

It worked. There is now a worldwide ban on CFC production (Australia since 1996).

First example of international and cross-disciplinary cooperation to address a global environmental issue

Poorer countries had longer to achieve CFC reduction.

Question 16

Oxygen-ozone equiplibrium

Answer 16

In the stratosphere O2 and O3 are in constant flux. Ozone molecules exist in the atmosphere for only a few minutes before either reacting or being broken down into its constituent parts.