Transcript Today (Tues 3/3)

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
1. Determine the sum of valence electrons.
CH4
CCl4
C: 4 Valence electrons
H: 1 Valence electron *4 atoms
Total: 8 electrons
C: 4 Valence electrons
Cl: 7 Valence electron *4 atoms
Total: 32 electrons
2. Use a pair of electrons to form a bond
between each pair of bonded atoms.
Cl
Used 8 in each
Cl
Cl
Cl
3. Arrange the remaining electrons to satisfy octet rule.
Used 8
.. Cl....
...
....
Cl
Cl
...
..
..Cl ..
..
Used 32
Molecular Shape Activity
Fig. 3.11 – Carbon Dioxide
Lewis structures
show connectivity.
Space-filling
Chargedensity
Fig. 3.8 - Methane
This Lewis
structure is
drawn in 3-D.
Figure 3.9: Ammonia
Fig. 3.10 - Water
Nitrate Ion, NO3O
O
O
O
N
N
N
O
O
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
The Earth’s Energy Balance
Greenhouse
effect
Our atmospheric
gases trap and
return a major
portion of the
heat radiating
from the Earth.
It is a natural,
necessary
process.
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
O
H
O
C
O
H
C
H
H
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 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
The Earth’s Energy Balance
Greenhouse
effect
Our atmospheric
gases trap and
return a major
portion of the
heat radiating
from the Earth.
It is a natural,
necessary
process.
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
O
dipole moment
dipole moment
H
O
C
O
no dipole moment
H
C
H
H
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 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
Loss of Polar Ice Cap
1979
2003
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 yearround, sea ice in the
Arctic is declining at a
rate of nine percent per
decade.
3.9
Loss of Polar Ice Cap
1979
As the oceans warm and ice thins,
more solar energy is absorbed by
the water, creating positive
feedbacks that lead to further
melting.
2003
Such dynamics can change the
temperature of ocean layers, impact
ocean circulation and salinity,
change marine habitats, and widen
shipping lanes.
3.9
The snows of Kilimanjaro
82% of ice field has
been lost since 1912
3.9
Main greenhouse gases
Water vapor
Carbon dioxide***
Methane
Chlorofluorocarbons (CFCs)
Tropospheric ozone
Nitrous 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
IR spectra of CO2 and other GHGs
http://chemistry.beloit.edu/Warming/pages/infrared.html
NOAA: National Oceanic and Atmospheric Administration
 Measuring CO2
http://www.esrl.noaa.gov/gmd/ccgg/about/co2_measurements.html
 Ice Core Data
http://www.ncdc.noaa.gov/paleo/icecore.html
 Oceans Warming
http://www.noaanews.noaa.gov/stories/s399.htm
National Glaciology Group, Canada
http://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.
Aerosols
In conclusion they act to cool the globe.
We produce a lot of them
Earlier models predicted warmer climates
than we are seeing
Aerosols 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/0116/ns_jeh.html
Climate forcing agents in the
industrial era (1850–2000) (W/m2).
Pinatubo
El Chichon
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.
Nobel Peace Prize 2007
http://www.ipcc.ch/ipccreports/tp-climatechange-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
How much will the Kyoto Protocol reduce emissions?
Business-as-usual
Kyoto Protocol scenario
Billion tons of carbon
8
6
8.0
7.6
6.4
5.8
4
2
0
1990
1995
2000
2005
Data Sources: United States Department of Energy, Energy Information Administration, International
Energy Outlook, 1998 and 1999.
2010
WORLD
RESOURCES
INSTITUTE
Bush Global Climate Change Initiative
 GHG intensity cut by 18% over next 10 yrs link
GHG emissions
 GHG intensity =
GDP
 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
US GHG Intensity
GHG Intensity
1.0
9500
9000
0.9
GHG Intensity
8500
8000
0.8
7500
0.7
7000
6500
0.6
GHG intensity
GHG emissions (Tg) CO2 eq
GDP 1995 $billion
0.5
1985
1990
1995
2000
2005
6000
5500
2010
Latest Data from EPA…
http://www.epa.gov/climatechange/emissions/downloads09/07Trends.pdf
Impacts of Global Warming
Drought and wildfire due to increased
evaporation
Sea level rise (10-25 cm increase to date;
48-95 cm by 2100) – inundation of lowlying areas
More intense rainstorms and more
hurricanes
Ecological 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
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!!
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 %
Keep these relationships in mind:
grams
use
molar
mass
moles
use
Avogadro’s
number
molecules
Remember – the critical link between moles
and grams of a substance is the molar mass
IT’S SIMPLE – THINK IN TERMS OF PARTICLES!
3.7
Quantitative Problems
Cover problems on chalkboard…
1.
2.
3.
4.
5.
6.
What is the molar mass of ammonia, NH3?
What is the mass ratio and mass % of nitrogen in ammonia?
For each mole of CH4 combusted, how many moles of CO2 and
H2O are formed?
How many CO2 molecules are formed when one mole of CH4 is
combusted?
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?
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.
2.
3.
4.
5.
6.
17.034 g/mol
0.822 g N per g NH3 or 82.2% N in NH3
For 1 mole of CH4 combusted, 1 mole of CO2 and 2 moles of H2O
are formed
6.02 × 1023 molecules of CO2
~8.8 kg CO2
1200 kg C
My car weighs 2000 kg!