today (tues 3/3) chapter 2 homework due newspaper articles: jeremy hendrickson and matt wood...
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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
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 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
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)
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 vibrations
MolesEnhanced 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)
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 know
1. 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
Main greenhouse gases
Water vaporCarbon dioxide***MethaneChlorofluorocarbons (CFCs)Tropospheric ozoneNitrous Oxide N2O
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
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
Laughing Gas, N2O
Sources Bacterial removal of nitrate ion (NO3
-) from soils
Ocean upwelling Statrospheric reactions NH3 fertilizers
Catalytic converters
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.
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
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
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
Billi
on ton
s of
car
bon
Business-as-usual
Kyoto 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
emissionsGHG
GDP
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 intensity
GHG emissions (Tg) CO2 eq GDP 1995 $billion
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 / atmosphere
Who 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!!
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!