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

C

H

H HH

109.5H H

H

H

C

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 radiationIR does not cause vibrationCan’t “trap” heatNot greenhouse gases

Fig.3.16

The Carbon Cycle

Sect. 3.5

Fig. 3.17

Where does CO2 come from?Where does it go?

Sources of CO2

CaCO3

(limestone)

water

Plants & animals

Respiration/decay

Volcanic ventsCO2

(natural)

Consumption of CO2

CO2Plants

Respiration waterH2CO3

Pressure/time

Fossil Fuels

Mineral Dep.

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

Mass #

Atomic #: 6

6p, 6n

One Carbon 12 = 12 amu

C6

Carbon

12.01

Atomic #

Symbol

Name

Atomic Mass

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

• 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