Topics for Today

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Topics for Today

• Ozone, the Good and the Bad
• Properties of Light

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Readings for Today

• Section 1.12 Tropospheric Ozone
• Section 2.1 What is ozone? Where is it?

Spectro-photometry Figure 5.23!
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Topics for Friday

• Sunscreen and UV light
• Quiz 4!

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Readings for Friday
Spectro-photometry Figure 5.23!
Section 2.4 Waves of Light
What is the difference between UV-A, UV-B, and
UV-C?
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Reminder
Assignment 2 is due by the beginning of lecture
on Friday!
Please email me (at least) a copy of your tables!
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Topics for Today

• Ozone, the Good and the Bad
• Properties of Light

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Criteria Pollutants

• Defined by the EPA
• CO
• SO2
• NOx
• PM2.5 and PM10
• O3

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(No Transcript)
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Why are the concentrations different on each day?
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How is ozone formed?
Is ozone a health hazard?
Why does ozone develop in the afternoon?
What is the ozone layer?
What is ozone?
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How is ozone formed?
Is ozone a health hazard?
Why does ozone develop in the afternoon?
What is the ozone layer?
What is ozone?
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O O2
O3 oxygen oxygen ozone
atom molecule
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oxygen
ozone
Oxygen atoms
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Whats wrong with this picture?
oxygen
ozone
Oxygen atoms
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oxygen
ozone
Oxygen atoms
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O. only exists in nature for VERY short amounts
of time Will react very quickly
Oxygen atoms
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O2 is somewhat reactive. Supports combustion
(does NOT burn)
oxygen
N2 O2 ? S O2 ? C O2 ? C8H18 O2 ?
?
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O3 is quite reactive (not as much as O., though)
ozone
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How is ozone formed?
Is ozone a health hazard?
Why does ozone develop in the afternoon?
What is the ozone layer?
What is ozone?
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NAAQS
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NAAQS
ppb?
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The NAAQS for ozone is 0.08 ppm
What is this in parts per 10 million?
0.8 !
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The NAAQS for ozone is 0.08 ppm
What is this in parts per 100 million?
8 !
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The NAAQS for ozone is 0.08 ppm
What is this in parts per billion?
80 ppb !
80 ppb 0.08 ppm 0.000008
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NAAQS
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NAAQS
How is ozone harmful to us?
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Ozone is a lung irritant
ozone
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Ozone irritates eyes
ozone
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Ozone Damages Plants
ozone
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Ozone Destroys Rubber
ozone
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How is ozone formed?
Is ozone a health hazard?
Why does ozone develop in the afternoon?
What is the ozone layer?
What is ozone?
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Easiest chemical reaction in the world

• O. O2 O3

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O2 is easy, where does the O. come from?

• O. O2 O3

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O2 O.
O.

• Lightning!

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O2 O.
O.

• Lightning!

Where are some of the highest concentrations of
ozone found?
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O2 O.
O.
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2
UV 242 nm

• O2 2O.

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2
Ultraviolet light is electromagnetic radiation!
UV 242 nm

• O2 2O.

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Figure 2.7 p. 76
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• UV VioletGreenYellowOrangeRed IR
• 400 nm 700 nm

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• UV VioletGreenYellowOrangeRed IR
• 400 nm 700 nm

242 nm
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ALL production of ozone happens this way,

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All natural sources

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All people sources

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So, just how do people create ozone (or O.)?
All people sources

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O2 is easy, where does the O. come from?

• 3. NOx!

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O2 is easy, where does the O. come from?

• 3. NOx!

REVIEW
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How is NOx formed by people?
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High temperature
N2 O2 2NO
Anywhere in the atmosphere you find HIGH
TEMPERATURES!!
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Summary

• N2 O2 2NO
• NO O2 .OH VOCs NO2 VOCs

high temp
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• OH. is the hydroxyl radical!
• OH- is the hydroxide ion!

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• 3. NOx!

END REVIEW
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How do we get O. from NOx??
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Summary
How do we get O. from NOx??

• N2 O2 2NO
• NO O2 .OH VOCs NO2 VOCs

high temp
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Visible light 600 nm

Visible light 600 nm

O.
NO2
NO
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(No Transcript)
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Which energy is greater?
Break O2 bond
Break NO2 bond
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Summary People Forming Ozone
Visible light 600 nm


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How is ozone formed?
Is ozone a health hazard?
Why does ozone develop in the afternoon?
What is the ozone layer?
What is ozone?
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First reaction
Visible light 600 nm

Visible light 600 nm

O.
NO2
NO
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• 1) When is most of the NOx formed?

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• 1) When is most of the NOx formed?

During the day!
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• 2) When are O. radicals formed?

Visible light 600 nm

O.
NO2
NO
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• 2) When are O. radicals formed?

During the day!
Visible light 600 nm

O.
NO2
NO
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Lets look at some real data

• 2) When are O. radicals formed?

During the day!
Visible light 600 nm

O.
NO2
NO
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Why the peaks?
Why no ozone peaks?
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• Ozone is not directly produced by humans!
• Ozone is a secondary pollutant

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How is ozone formed?
Is ozone a health hazard?
Why does ozone develop in the afternoon?
What is the ozone layer?
What is ozone?
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• The ozone layer
• So far, weve only talked about ozone at ground
  level (in the troposphere)!

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Miles
Miles
http//www.windows.ucar.edu/earth/images/atmospher
e_mural.jpg
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Miles
Why is there an ozone layer?
Miles
http//www.windows.ucar.edu/earth/images/atmospher
e_mural.jpg
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What if there were O2 here?
30 miles
15 miles
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UV 242nm
O2 ? 2O.
30 miles
15 miles
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UV 242nm
O2 ? 2O.
30 miles
What goes on here?
15 miles
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UV 242nm
O2 ? 2O.
30 miles
O. O2 ? O3
15 miles
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Topics for Today

• Ozone, the Good and the Bad
• Properties of Light

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How does light interact with matter?
What do we know about light?
Shorter Wavelength Higher Energy
Longer Wavelength Lower Energy
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Light Can Be
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Light Can Be
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Nitrogen, N2
Oxygen, O2
About 99 of the atmosphere
Do these transmit light?
YES NO MAYBE
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Nitrogen, N2
Oxygen, O2
About 99 of the atmosphere
Do these transmit light?
YES NO MAYBE
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Do sunglasses transmit light?

• Transmission of light When equal amounts of
  light enter and exit an object.
• No change in wavelength (energy)

VISIBLE LIGHT IN
Equal Amounts OUT
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Light Can Be
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Do sunglasses reflect light?
Equal amounts of light are reflected off of a
surface. No change in wavelength (energy)
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Light Can Be
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Light can be absorbed! The amount outgoing light
is LESS than the incoming light. Only for a
particular energy.
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Do sunglasses absorb light?
Where have we seen the absorption of light in
Chem 108?