Chapter 3
The Chemistry of Global Warming


Earth Atm. @ 1x had 1000x more CO2
Where did it go?
Dissolved in oceans
Fixed as CaCO3 - limestone

SUN < 25-30% - ?

Early Pollution was O2!
6CO2 + 6H2O ---> C6H12O6 + 6O2


Photosynthesis* - chlorophyll used Sun E to change CO2 & H2O into Glucose & O2
(*note to future teachers - this is in every 3-6 curriculum)

Temperature & CO2 content have changed over time
Factors that caused temp. change

1) Fluctuations in Earth’s Orbit
a) distance
b) angle of incidence

2) Terrestrial events
a) reflectivity
b) cloud cover
c) airborne dust
d) CO2 & CH4 conc.
These feedback mechanisms are poorly understood.

Earth’s Energy Balance
(OH & fig 3.2)

Greenhouse Effect
-
my nifty drawing
84 % of heat reradiated is absorbed by the atmo.

If we release/increase gases? (fig. 3.3)

Molecular Shapes
.. ..
:N:::N: O::O

.. ..


Maximize distance between e-


CH4

H
..
H :C: H
..
H


Lewis Dot Structure - do not show actual shape ( geometry) tetrahedron - 109.5

1)Electron pairs in a molecule are usually arranged in such a way that they are as far from each other as possible.

2) Bonding pairs have less space requirements than non bonding.

..
H2O ---> H:O: H
  ..
:O:
 / \
H H
-140.5- .. ..
CO2---> O::C::O
.. ..
.. ..

O=C=O
.. .. 1800


Why all this fuss about shape?

IR radiation does NOT have enough E to break bonds but it will cause a molecule to vibrate.

Molecular structure determines
• type of vibration
• each vibration has characteristics Set of E - Levels \diff. mol. absorb E @ diff l.

Amount of E required varies with
1. Nature of motion
2. strength
3. “stiffness”
4. mass of atom

Fig 3.5 & 3.6 (p.84-85)
valley -absorbed


THE CARBON CYCLE (fig 3.8)

(203)(207)
Question this chart! .5%.

photosynthesis - 110/203 = 54%

the other 46 % is dissolved in oceans, animal shells, rocks

Another dynamic, steady state system!
How is it returned?
• Death and Decay ---> CO2
• Broken Down ---> CO2
• Animals ---> CO2
• volcanoes, weathering ---> ?

Atomic Mass

Carbon - 12 (Carbon-12 is standard)

Isotopes

C-12 = 98.9%
C-13 1.19%
C-14 - 1 x 1012 --> radioactive

But how would we measure .1 mg?

.1 mg---> 1x10-4g ---> 5x1018 atoms C
not our scales!

Avogadro’s Number

is 6.02x1023 or 1 mole

(note examples p. 91 - 93)

1
C + 1 O2 ---> 1 CO2
1 mole C x 12.0 g/mole C = 12g
+ 2 mole O x 16.0 g/mole O = 32 g
molar mass of CO2 is 44 g
molecular wt. - old term


CLIMATIC MODELING


Needs
1. astronomy
2. meteorology MODELS
3. geology
4. biology

Example:
in Ocean Temp. causes aØ CO2 solubility which causes an in CO2 atoms which Ocean temp. so phytoplankton , which Ø CO2 in the atmo. so that there is a in CO2 fixing
\ Ø in atmo temp, which Ø ocean temp


WAIT A MINUTE !!!! BUT YOU SAID ...
global temp, evap, transpiration, clouds which reflect sunlight which lead to Ø in global temp or in global temp b/c H2O greenhouse gas

What to do? What to do?


1. Study & (maybe forever) wait
2. Do SOMETHING!!! The Chicken Littles
3. What do you want from life? Live with it


My View (happens to coincide w/text)

1. Careful study
2. Extensive monitoring - improves reliability
3. Appropriate technology
4. EDUCATED, INFORMED & RESPONSIBLE public


and yet you can never be absolutely sure -oops
Existential, man!