Transcript The Future (?) - University of Missouri

The Future (?)
Data from past 100 years:
CO2 conc. has risen by 25%
average temp. increase: 0.5-0.7 0C
Current: doubling the CO2 conc.  +1.8-6.3 0C
(2.5-10.4 0F by 2100)
CO2 is a major part of the greenhouse effect
Earth’s average temperature is increasing
Shape of Molecules (3.3)
Greenhouse gases:
CO2, CH4, N2O, O3, H2O, CFCs
Not greenhouse gases:
O2, N2, Ar
Why the difference? Shape!
VSEPR
Lewis structures: 2D
Reality: 3D
Bonds are made of electrons
Negatively charged
Repel each other (still attracted to protons)
Want to be as far apart as possible!
Example: Methane
CH4: tetrahedral
H
H
C
H
H
H
109 .5
C
H
H
H
Fig.3.7
Fig.3.8
Fig.3.9
“Trigonal Pyrimidal”
Fig.3.10
“Bent”
Fig.3.11
“Linear”
Fig.03.12
“Bent”
Light and Molecules (3.4)
UVB, UVC: Bonds break
IR: Can’t break (not enough energy)
Can cause vibrations
Shape  HOW a molecule can vibrate
Which wavelength?
Bond strength & flexibility, atom masses
Fig.03.13
Fig.3.14
What about O2 and N2?
Do not absorb IR radiation
IR does not cause vibration
Can’t “trap” heat
Not greenhouse gases
Fig.3.16
The Carbon Cycle
Sect. 3.5
Where does CO2 come from?
Where does it go?
Fig. 3.17
Sources of CO2
(natural)
CaCO3
(limestone)
water
CO2
Respiration/decay
Plants & animals
Volcanic vents
Consumption of CO2
Respiration
Plants
water
CO2
Mineral Dep.
Pressure/time
Fossil Fuels
H2CO3
Fossil Fuel Contribution to
Atmospheric CO2:
• 6-7 billion tons of carbon released
• ~ ½ goes to atmosphere
• Since 1860:
– CO2 conc. 290 ppm  375 ppm,
– Increases ~1.5 ppm/year.
Deforestation
• Adds CO2 to air
(burning/decay)
• Takes away a CO2 remover (trees/plants)
• Excess CO2  global warming
• Increase in atmos. CO2 is a concern
– 3.1-3.5 Gt of carbon/year
• How much CO2 is added per year?
Quantitative Concepts: Mass (3.6)
How much does an atom weigh?
Depends on the atom
Standard: Carbon-12
Atomic #: 6
6p, 6n
Mass #
One Carbon 12 = 12 amu
Atomic #
Symbol
Name
6
C
Carbon
12.01
Atomic
Mass
What’s with the 12.01???
Carbon: 3 isotopes
Carbon-12: 98.89%
Carbon-13: 1.11%
Carbon-14: ~0.00%
Average atomic mass for C = 12.01 amu
Atomic mass is an average
of all carbon atoms
• NO carbon atoms weigh 12.01 amu
• Treat ALL carbon atoms as though they
weigh 12.01
• 1 Tbs of carbon has about
6.022 x 1023 carbon atoms
– 602,200,000,000,000,000,000,000
• Dealing with large numbers of atoms
– Average is best