Today (Tues 3/3)

• Chapter 2 Homework Due• Newspaper Articles: Jeremy Hendrickson

and Matt Wood• Molecular Shape Activity• Start Chapter 3 notes• Laboratory: Greenhouse Gases Lab

Review: How to draw Lewis structures

2. Use a pair of electrons to form a bond between each pair of bonded atoms.

3. Arrange the remaining electrons to satisfy octet rule.

1. Determine the sum of valence electrons.CH4 CCl4

C: 4 Valence electronsH: 1 Valence electron *4 atomsTotal: 8 electrons

C: 4 Valence electronsCl: 7 Valence electron *4 atomsTotal: 32 electrons

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl

..

..

.. ...... ..

......

....

Used 8 in each

Used 8 Used 32

Molecular Shape Activity

Fig. 3.11 – Carbon Dioxide

Lewis structuresshow connectivity.

Space-filling Charge- density

Fig. 3.8 - Methane

This Lewis structure is drawn in 3-D.

Figure 3.9: Ammonia

Fig. 3.10 - Water

Nitrate Ion, NO3-

N

O

O ON

O

O ON

O

O O

Fig. 3.12 - Ozone

Summary of Molecular Shape Activity: Valence Shell Electron Pair Repulsion Theory

• Assumes that the most stable molecular shape has the electron pairs surrounding a central atom as far away from one another as possible.

• Molecules can be classified into shape categories.

• If there are lone pairs on the central atom, the bond angles will be smaller than predicted.

Chapter 3: The Chemistry of Global Warming

Chapter 3 Learning Objectives• The greenhouse effect • Molecular structure and shape

– Why are some molecules greenhouse gases (absorb IR radiation)

– Molecular vibrations• Moles• Enhanced Greenhouse Effect andGlobal Climate

Change• Global Climate Change Models• Global Climate Change Policy

Greenhouse effect

Our atmospheric gases trap and return a major portion of the heat radiating

from the Earth.

It is a natural, necessary process.

The Earth’s Energy Balance

Figures Alive

What makes a gas a greenhouse gas?

• IR absorption is related to molecular structure

• Dipole moment – separation of charge– Electron density is not uniform in the molecule

resulting in partial electrical charges

Which of the following molecules have a dipole moment?H2O, CO2, O3, and CH4

O HH

OO

O

CO O C

H

H

HH

To absorb IR radiation…

• Energy of IR radiation must match the vibration energy of the molecule

• For us to see absorbtion of IR radiation on a spectrometer the dipole moment (charge distribution) must change

• IR Tutor– Units on IR spectra are wavenumbers, cm-1

– Wavenumber = 1/wavelength (in cm)

Fig. 3.14 – IR spectra of CO2

Fig. 3.15 – IR spectra of H2O

Stretching

Bending

Why aren’t O2 and N2 greenhouse gases?

Why doesn’t the IR radiation coming from the sun also cause a

greenhouse effect?

Today (Thurs 3/5)• Newspaper Articles: Eric Noun and Steve

Andres• Chapter 3 notes: ‘review and new’• Focus Group project – Evaluation of

Example Papers

Chapter 3 Learning ObjectivesThe greenhouse effect Molecular structure and shape

Why are some molecules greenhouse gases (absorb IR radiation)

Molecular vibrationsMolesEnhanced Greenhouse Effect andGlobal Climate

ChangeGlobal Climate Change ModelsGlobal Climate Change Policy

Greenhouse effect

Our atmospheric gases trap and return a major portion of the heat radiating

from the Earth.

It is a natural, necessary process.

The Earth’s Energy Balance

Figures Alive

What makes a gas a greenhouse gas?

IR absorption is related to molecular structure

Dipole moment – separation of charge Electron density is not uniform in the molecule

resulting in partial electrical charges

Which of the following molecules have a dipole moment?H2O, CO2, O3, and CH4

O HH

dipole moment

OO

O

CO O

no dipole moment

dipole moment

C

H

H

HH

no dipole moment

To absorb IR radiation…

Energy of IR radiation must match the vibration energy of the molecule

For us to see absorbtion of IR radiation on a spectrometer the dipole moment (charge distribution) must change Units on IR spectra are wavenumbers, cm-1

Wavenumber = 1/wavelength (in cm)

Fig. 3.14 – IR spectra of CO2

Fig. 3.15 – IR spectra of H2O

Stretching

Bending

The Greenhouse Effect Established Proven Fact Not controversial Temperature of the earth would be ~60 F cooler without the

Greenhouse Effect Global Warming is the theory that the greenhouse effect has

been enhanced by carbon dioxide and other greenhouse gases

Amplification of Greenhouse Effect:

Global Warming:

What we know1. CO2 contributes to an elevated global temperature.

2. The concentration of CO2 in the atmosphere has been increasing over the past century.3. The increase of atmospheric CO2 is a consequence of human activity.4. Average global temperature has increased over the past century.

3.2

What might be true:

1. CO2 and other gases generated by human activity are responsible for the temperature increase.

2. The average global temperature will continue to rise as emissions of anthropogenic greenhouse gases increase.

3.8

NASA Study: The Arctic warming study, appearing in the November 1 2003 issue of the American Meteorological Society's Journal of Climate, showed that compared to the 1980s, most of the Arctic warmed significantly over the last decade, with the biggest temperature increases occurring over North America.

Perennial, or year-round, sea ice in the Arctic is declining at a rate of nine percent per decade.

Loss of Polar Ice Cap

1979

2003

3.9

Loss of Polar Ice Cap

As the oceans warm and ice thins, more solar energy is absorbed by the water, creating positive feedbacks that lead to further melting.

Such dynamics can change the temperature of ocean layers, impact ocean circulation and salinity, change marine habitats, and widen shipping lanes.

1979

2003

3.9

82% of ice field has been lost since 1912

The snows of Kilimanjaro

3.9

Main greenhouse gases

Water vaporCarbon dioxide***MethaneChlorofluorocarbons (CFCs)Tropospheric ozoneNitrous Oxide N2O

Fig. 3.17 Carbon Cycle

Fig. 3.4

CO2 and Temperature

McMurdo Station, Antartica Ice Core Ice Layers Drilling Tent

Fig. 3.5 CO2 concentrations by ice core and IR data

Cool Links

NOAA: National Oceanic and Atmospheric Administration

Measuring CO2

Ice Core Data

Oceans Warming

http://chemistry.beloit.edu/Warming/pages/infrared.html

http://www.esrl.noaa.gov/gmd/ccgg/about/co2_measurements.html

http://www.noaanews.noaa.gov/stories/s399.htm

IR spectra of CO2 and other GHGs

http://www.ncdc.noaa.gov/paleo/icecore.html

National Glaciology Group, Canadahttp://cgc.rncan.gc.ca/glaciology/national/drill_e.php

CO2 trends•CO2 increasing ~2.1 ppm/yr (for 2001-2005)•1963 increase = 0.76 ppm•1998 increase = 2.87 ppm (biggest leap)•2002 increase = 2.1 ppm•2007 increase = 2.4 ppm

http://www.esrl.noaa.gov/gmd/publications/annmeet2006/pdf_2006/talks%202006%202.pdf

Today (Tues 3/10)• Newspaper Presentations: Brock Hill and

Andrew Griesman• GHGs and IR Spectra (Lab Prep)• Library Time (~3-4:20)

For Next Time (Thurs 3/12)• Print new slides (I added some to the end)• Read Chapter 3• Work on Homework 3

Why is CO2 increasing?

Burning fossil fuels converts the carbon in the fuels to carbon dioxide (CO2) Fossil fuels = coal, gasoline, natural gas

Actually CO2 levels have not increased in the atmosphere as much as predicted Also been contended that CO2 levels have

increased due to temperature increasing Scientific understanding is key – models

developed

CO2 IR Spectra

Tab. 3.2

Methane

Sources: ~40 % Natural Sources

Natural Gas escaping from rocks Decaying plant material in wetlands

Agriculture Rice Paddies (Anaerobic Bacteria) Cattle (~500 L of CH4 per day!)

Landfills Termites Release from oceans, bogs, permafrost

IR Spectra of Methane

CO2 Contamination

Laughing Gas, N2O

Sources Bacterial removal of nitrate ion (NO3

-) from soils

Ocean upwelling Statrospheric reactions NH3 fertilizers Catalytic converters

IR spectra of Water vapor

CO2 Contamination

IR Spectra of some GHGs

Tab. 3.3

The bigger the number, the greater the effect.

Today (Thurs 3/12)• Newspaper Articles: Tom Jaede• Can we have global cooling? • Global Climate Change Models• Global Climate Change Policy• Group Activity

For Next Time (Tues 3/17)• Finish reading Chapter 3• Homework #3 Due• Start studying for the exam (on 3/19) –

bring questions to class!

Aerosols and Particulates Aerosol = small atmospheric particle; can be a

solid particle, liquid suspension, or combination Subject to Brownian motion…don’t settle for a

long time. ( unlike bigger particles which settle out quickly).

Coal combustion sulfates Sulfates seed condensation clouds Aerosol particles and clouds reflect incoming

radiation - this is a cooling effect However, some aerosols are black and absorb

radiation

Volcanoes Mt Pinatubo in Phillipines

erupted in 1991 20 million tons of sulfur

dioxide and particulates into the stratosphere

Particulates reflected sunlight in the stratosphere before the radiation got to the troposphere.

Cooled the planet for 2 years.

AerosolsIn conclusion they act to cool the globe.We produce a lot of themEarlier models predicted warmer climates

than we are seeingAerosols are off-setting some effects of

the increase in greenhouse gases.

Modeling Global Warming…

Climate “Forcing”

A relatively simple way to look at climate change “Climate Forcing” – an imposed perturbation on

the earth’s energy balance Positive forcing – adds energy – creates warming Negative forcing – reduces energy – leads to cooling

Climate models predict: Forcing of ± 1 W/m2 = ± 3/4oC (equilibrium) This relation consistent with last Ice Age

James Hansen (NASA) http://naturalscience.com/ns/articles/01-16/ns_jeh.htm

l

Climate forcing agents in the industrial era (1850–2000) (W/m2).

El Chichon

Pinatubo

Fig. 3.22

Worldwide Emissions and Policies

Fig. 3.23

Good Source for Additional Data: http://cdiac.ornl.gov/trends/emis/meth_reg.html

Fig. 3.27

Page. 147.2

Policy History 1988 IPCC (Intergovernmental Panel on Climate

Change) established by World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP)

1992 Earth Summit 1997 Kyoto Conference 2007 IPCC states in a report that scientific

evidence for global warming was unequivocal and that human activity is the main cause.

What IPCC Does… Run from offices in Geneva, but open to any of the nearly

200 member states belonging to the UN or WMO

Functions through its working groups focusing on the science, impact and mitigation of climate change, and developing greenhouse gas inventories.

The findings of the IPCC are presented as 'Assessment reports', synthesizing the views of the working groups, which are produced approximately every 5 years.

The fourth and next report is due at the end of 2007.

Back

Nobel Peace Prize 2007http://www.ipcc.ch/ipccreports/tp-climate-

change-water.htm

Nobel Peace Prize Laureates Al Gore (left) and R. K. Pachauri, Chairman of the Intergovernmental Panel on Climate Change (IPCC) with their Nobel Peace Prize Medals and Diplomas at the Award Ceremony in Oslo, Norway, 10 December 2007.

R. K. Pachauri will be at Gustavus for Nobel 2009!

The Kyoto Protocol 160 nations met in Kyoto Japan in 1997 to negotiate

the Protocol The protocol states that developed nations will limit

GHG emissions at 5% below 1990 levels (US 7%) CO2, CH4, NO, HFC’s, PFC’s, and SF6

Short-term goals; no long-term fixes (major criticisms)

Emissions could be traded Credits for creating carbon sinks? -removed U.S. signed the Protocol but would not ratify it

Kyoto went into effect Feb 16, 2005 w/o the US participating

Who has ratified - who hasn’t

Protocol went into effect when 55 parties representing 55% of heat-trapping emissions have ratified

All 15 nations in the European Union have ratified, Canada and Japan

Russia ratified in November 2004, Protocol went into effect in February 2005

US is responsible for ~25% of carbon emissions Developed nations emit about 62% of carbon

emissions

What would U.S. have to do to meet emission requirements

We could easily reduce emissions by 7% by simply conserving, raising fuel mileage stds, increasing investment in renewable energy

US already 13% above 1990 emissions link ~20% reduction would be required

Any policy to reduce emissions will have significant implications for energy industry and the whole U.S. economy. We need more energy

Commitment period would be between 2008-2012

back

National Policy: What has the Bush Administration Done?

During 2000 campaign President Bush promised mandatory reduction targets for CO2 emissions

The Kyoto Protocol is fatally flawed – India and China are not required to do anything– the Protocol would hurt the economy Most future GHG emissions will come from

developing nations and they aren’t required to do anything! - besides we need to meet future energy needs and our economy has become more energy efficient

Kyoto doesn’t solve the problem anyways

WORLDWORLDRESOURCESRESOURCESINSTITUTEINSTITUTE

Data Sources: United States Department of Energy, Energy Information Administration, International Energy Outlook, 1998 and 1999.

How much will the Kyoto Protocol reduce emissions?

8.0

5.8

7.6

6.4

0

2

4

6

8

1990 1995 2000 2005 2010

Billio

n ton

s of c

arbo

nBusiness-as-usualKyoto Protocol scenario

Bush Global Climate Change Initiative GHG intensity cut by 18% over next 10 yrs link GHG intensity =

GHG emissions allowed to increase by 31% over this time (assumes GDP increase is 3.3%/yr); GHG intensity decreased 17% in the 90s

“This goal is comparable to the avg progress that nations…in Kyoto Protocol are required to achieve”

Yes, because Kyoto requires nothing of developing nations “as the science justifies” The data are very clear – the earth has warmed and

considering only extreme weather events, the cost to the US was over $40 billion dollars in 2004

emissionsGHGGDP

GHG IntensityUS GHG Intensity

1985 1990 1995 2000 2005 2010

GH

G In

tens

ity

0.5

0.6

0.7

0.8

0.9

1.0

5500

6000

6500

7000

7500

8000

8500

9000

9500

GHG intensityGHG emissions (Tg) CO2 eq GDP 1995 $billion

Latest Data from EPA…

http://www.epa.gov/climatechange/emissions/downloads09/07Trends.pdf

Impacts of Global WarmingDrought and wildfire due to increased

evaporationSea level rise (10-25 cm increase to date; 48-

95 cm by 2100) – inundation of low-lying areas More intense rainstorms and more hurricanesEcological Impacts

Migration, breeding, population, species composition, lakes/fish, forests, coral reefs

What would we have to do to curtail warming?

Burn less fossil fuels Increase the cost (carbon tax – tax on gas, coal, and

natural gas burning) More efficient vehicles, houses, appliances, etc.

Use non-carbon based or renewable fuels Wind energy, solar energy Hydrogen fuel cells Ethanol, biodiesel

Remove CO2 from emissions / atmosphereWho is responsible?

Group Activity To stabilize the current climate, scientists estimate an

80% reduction in greenhouse gas emissions is necessary

Within in your group choose one of the three scenarios Immediate, significant greenhouse gas emission reductions Gradual reductions of greenhouse gas emissions

Next, give suggestions for how you would make your scenario a reality Why do you think this approach is best? What are the pros and

cons of your approach? Are you free to realize the environmental future that you envision?

Today (Tues 3/17)• Newspaper Articles: Peter Dierauer, Wai

Yang• Discussion: Obama Administration• Finish Chapter 3 notes• In-class worksheet on Chapter 3• Lab time: Optional Exam Review

For Next Time (Thurs 3/19)

First Exam!!First Exam!!

Tab. 3.6

The Mole

The mole

Avogadro’s number – 6.02 x 1023 of anything per mole (anything = atoms, molecules, etc.)

Molar mass or molecular weight is usually expressed as grams per mole

What are the molar masses or molecular weight of C and CO2?

Carbon in CO2-mass ratios and mass %

moles moleculesgramsusemolarmass

useAvogadro’s number

IT’S SIMPLE – THINK IN TERMS OF PARTICLES!

Keep these relationships in mind:

3.7

Remember – the critical link between moles and grams of a substance is the molar mass

Quantitative Problems

Cover problems on chalkboard… 1. What is the molar mass of ammonia, NH3?

2. What is the mass ratio and mass % of nitrogen in ammonia? 3. For each mole of CH4 combusted, how many moles of CO2 and

H2O are formed?

4. How many CO2 molecules are formed when one mole of CH4 is combusted?

5. There are 2.4 kg of C in a gallon of gasoline, how much CO2 is emitted from your tailpipe when you burn 1 gallon of gasoline?

6. My car gets 20 miles/gallon. If I drive 10,000 miles a year, how much C (in kg) is emitted each year?

My car weighs 2000 kg!

Quantitative Problems

Answers to problems on chalkboard… 1. 17.034 g/mol2. 0.822 g N per g NH3 or 82.2% N in NH3

3. For 1 mole of CH4 combusted, 1 mole of CO2 and 2 moles of H2O are formed

4. 6.02 × 1023 molecules of CO2

5. ~8.8 kg CO2

6. 1200 kg C

My car weighs 2000 kg!