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Earth as a Closed SystemEarth as a Closed System
The Earth’s Atmosphere
• 78% Nitrogen• 20% Oxygen• 1% Argon
• 0.03% CO2
• Trace Elements
‘The Precious Envelope’
Helium
NitrogenOxygen
Watervapor
Argon
Neon
Carbondioxide
Air
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Component Percent composition
Nitrogen, N2 78%Oxygen, O2 21%Argon, Ar 0.9%Water, H2O 0 – 4% (variable)Carbon dioxide, CO2 0.034% (variable)
The Earth’s AtmosphereFrom Space
Light fromthe sun
Reflected heatabsorbed byatmosphere
Reflected heat lost toouter space
Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 392
Global Warming
HIGH ENERGY, SHORT LIGHT PASSESEASILY THROUGH ATMOSPHERE
ENERGY RELEASEDAS HEAT
LOWER ENERGY, LONGER LIGHT IS BLOCKED BY CO2
AND CH4; ENERGY DOESN’T
ESCAPE INTO SPACE;ATMOSPHERE HEATS UP
CO2 MOLECULES
The Greenhouse Effect
Greenhouse Gases
The Earths Atmosphere
Ozone
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 309
Carbon Dioxide Levels
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 310
350
300
250
1000 1500 2000
Year
Atm
osph
eric
C
O2
(ppm
)
(a) Records from Antarctic ice cores (1006-1969 A.D.) (b) Records from monthly air samples, Mauna Loa Observatory, Hawaii (1958-2002)
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Why more CO2 in atmosphere now than 500 years ago?
burning of fossil fuels deforestation
* The burning of ethanol won’t slow greenhouse effect.
C2H5OH + O2 CO2 + H2O
-- coal-- petroleum-- natural gas-- wood
-- urban sprawl-- rain forests-- wildlife areas
• FACT: 15% increase in [CO2] in last 100 years• Cause:
– Change from agricultural to industrial lifestyle– Burning of fossil fuels (petroleum, coal) – Increase CO2 emissions (cars, factories etc…)– Deforestation
• Effects: – Global warming – Melt polar ice caps flooding at sea level– Warming oceans more powerful storms
Greenhouse Effect
350
300
2501000 1500 2000
Year
Atm
osph
eric
C
O2
(ppm
)
Greenhouse Effect
Children and pets left unattended in vehicles with windowsrolled up can die from high temperature in vehicle.
Carbon dioxide in atmosphere traps heat and acts like aglass cover holding in the heat on planet Earth.
insulate home; run dishwasher full; avoid temp. extremes (A/C &
furnace); wash clothes on “warm,” not “hot” mow lawn less often (small
engines)
What can we do?
1. Reduce consumption of fossil fuels.
2. Support environmental organizations.
3. Rely on alternate energy sources.
bike instead of drive; carpool;energy-efficient vehicles
At home:
On the road:
solar, wind energy, hydroelectric power
Sources of Energy
