The Future (?)
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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!
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
What about O2 and N2?
Do not absorb IR radiationIR does not cause vibrationCan’t “trap” heatNot greenhouse gases
Sources of CO2
CaCO3
(limestone)
water
Plants & animals
Respiration/decay
Volcanic ventsCO2
(natural)
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.
• 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
Mass #
Atomic #: 6
6p, 6n
One Carbon 12 = 12 amu
Carbon: 3 isotopes Carbon-12: 98.89% Carbon-13: 1.11% Carbon-14: ~0.00% Average atomic mass for C = 12.01 amu
What’s with the 12.01???
Atomic mass is an average of all carbon atoms