RESOURCES

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RESOURCES

• AS Level

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THE GREENHOUSE EFFECT - GLOBAL WARMING
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LEARNING OUTCOMES

• Explain that infrared radiation is absorbed by
  CO, OH and CH bonds in CO2, H2O and CH4, and
  this contributes to global warming.
• Explain that the greenhouse effect of a given gas
  is dependent both on its atmospheric
  concentration and its ability to absorb infrared
  radiation.

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THE GREENHOUSE EFFECT DEFINITION

• The greenhouse effect is the process in which
  the absorption and subsequent emission of
  infrared radiation by atmospheric gases warms the
  lower atmosphere and the planets surface.

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• What has this got to do with chemistry???

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THE GREENHOUSE EFFECT
energy from the sun is in the ultra violet,
visible and infra red regions
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THE GREENHOUSE EFFECT
energy from the sun is in the ultra violet,
visible and infra red regions
47 reaches the earth
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THE GREENHOUSE EFFECT
energy from the sun is in the ultra violet,
visible and infra red regions
47 reaches the earth
radiation re-emitted from the earth is in the
infra red region
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THE GREENHOUSE EFFECT
energy from the sun is in the ultra violet,
visible and infra red regions
47 reaches the earth
radiation re-emitted from the earth is in the
infra red region
70 of the radiation returns to space
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THE GREENHOUSE EFFECT
energy from the sun is in the ultra violet,
visible and infra red regions
47 reaches the earth
radiation re-emitted from the earth is in the
infra red region
70 of the radiation returns to space
greenhouse gases absorb the remainder
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THE GREENHOUSE EFFECT
energy from the sun is in the ultra violet,
visible and infra red regions
47 reaches the earth
radiation re-emitted from the earth is in the
infra red region
70 of the radiation returns to space
greenhouse gases absorb the remainder
energy is returned to earth to keep it warm
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Carbon dioxide and water molecules will vibrate
as energy is absorbed
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GREENHOUSE GASES
Different covalent bonds have different strengths
due to the masses of different atoms at either
end of the bond. As a result, they vibrate at
different frequencies (imagine two balls on
either end of a spring) . The frequency of
vibration can be found by detecting when the
molecules absorb electro-magnetic radiation.
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GREENHOUSE GASES
Different covalent bonds have different strengths
due to the masses of different atoms at either
end of the bond. As a result, they vibrate at
different frequencies (imagine two balls on
either end of a spring) . The frequency of
vibration can be found by detecting when the
molecules absorb electro-magnetic
radiation. Various types of vibration are
possible. Bending and stretching are two
examples and are found in water molecules. Each
occurs at a different frequency.
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GREENHOUSE GASES
Different covalent bonds have different strengths
due to the masses of different atoms at either
end of the bond. As a result, they vibrate at
different frequencies (imagine two balls on
either end of a spring) . The frequency of
vibration can be found by detecting when the
molecules absorb electro-magnetic
radiation. Various types of vibration are
possible. Bending and stretching are two
examples and are found in water molecules. Each
occurs at a different frequency. Symmetric
Bending
Asymmetric stretching stretching
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GREENHOUSE GASES
Different covalent bonds have different strengths
due to the masses of different atoms at either
end of the bond. As a result, they vibrate at
different frequencies (imagine two balls on
either end of a spring) . The frequency of
vibration can be found by detecting when the
molecules absorb electro-magnetic
radiation. Various types of vibration are
possible. Carbon dioxide also undergoes bending
and stretching. Bending in a carbon
dioxide molecule
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DETECTING GREENHOUSE GASES
The frequencies lie in the INFRA RED part of the
electromagnetic spectrum and can be detected
using infra red spectroscopy. An infra red
spectrum of atmospheric air .
H2O
CO2
CO2
H2O
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THE GREENHOUSE EFFECT SUMMARY

1. The Earth receives most of its energy in the form
   of electromagnetic radiation from the Sun. (Most
   from visible, some from UV and IR regions).
2. The incoming radiation is relatively unaffected
   by the gases in the Earths atmosphere.
3. Most IR radiation goes back into space, however
   certain gases absorb this radiation, some is
   re-emitted back towards the Earth.
4. This traps the heat in the lower atmosphere.

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The greenhouse effect isnt all bad

• Without greenhouse gases our planet would be
  covered in ice with an average temperature 35oC
  less than present.

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• The temperature of our planet has more to do
  with the greenhouse effect than with our
  proximity to the sun!

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THE GREENHOUSE EFFECT

• The greenhouse effect creates an equilibrium.
• The atmospheric gases absorb energy at the same
  rate it radiates it, thus maintaining a steady
  temperature.

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GREENHOUSE GASES
CARBON DIOXIDE CO2 contains C O bonds WATER
VAPOUR H2O contains O - H bonds METHANE CH4 cont
ains C - H bonds The Greenhouse Effect of a
given gas is dependent on its... atmospheric
concentration ability to absorb infrared
radiation
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THE THREE MAIN GREENHOUSE GASES

• Water vapour from evaporation of lakes and
  oceans. Most abundant.
• Carbon dioxide produced by volcanic eruptions,
  respiration of animals and burning of organic
  matter (plants).

Methane emitted during the production of fossil
fuels, rotting waste in landfill sites and
released from certain animals (cows). Least
amount but greatest contributor.
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• Clathrates contain 3000x as much methane as
  found in the atmosphere, if released this would
  have a huge effect on greenhouse gases.

There is some speculation that release of these
methane bubbles have added to global warming, but
there is no concrete proof.
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SO WHATS THE PROBLEM?

• The greenhouse effect is a natural process,
  keeping our planet at a temperature capable of
  supporting life.
• The problem Human activity is producing more
  greenhouse gases, which threaten to upset this
  fine natural balance, resulting in global
  warming.

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An increase in the concentration of greenhouse
gases leads to climate change / global warming.
What do you think?
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GLOBAL WARMING POTENTIAL (GWP)

• The ability of a trace gas to cause global
  warming is described by its GWP.
• GWP is related to the lifetime of a gas in the
  atmosphere as well as the ability of a gas to
  absorb IR radiation.
• Since banning use of CFCs their effect is
  diminishing.

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QUESTIONS

1. Name the three greenhouse gases
2. Outline the molecular processes that enable heat
   to be kept close to the Earth.
3. What factors contribute to a gass contribution
   to global warming?

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CLIMATE CHANGE
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Learning objectives

• Explain the importance of controlling global
  warming caused by atmospheric increases in
  greenhouse gases.
• Outline the role played by chemists through the
  provision of scientific evidence that global
  warming is taking place.
• Understand the role of chemists in monitoring
  progress of initiatives such a Kyoto protocol.

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WHAT IS CLIMATE CHANGE?

• An increase in the concentration of greenhouse
  gases leads to climate change / global warming.
• Global warming is defined as an increase in the
  average temperature of the Earths atmosphere,
  especially a sustained increase big enough to
  cause climate change
• What does this mean?

• The temperature goes up (warmer summers, mild
  winters)
• Plants and crops may not be able to grow in the
  same places
• Extreme storms, hurricanes and floods may become
  more common
• Sea levels may rise causing flooding

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HOW DO WE FIND OUT IF GLOBAL WARMING IS HAPPENING?
We need to record the temperature and the weather
at lots of places across the Earth. After many
years, we can see a pattern in the
data. Scientists try to decide what the pattern
means.
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GLOBAL WARMING CAN BE SEEN IN

• In the Arctic, ice and permafrost disappearing
• In the Antarctic, ice sheets melting into the
  oceans
• Tropical areas experiencing more frequent and
  destructive storms and floods
• In Europe, glaciers are disappearing and there
  have been extreme heat waves.

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REDUCING GREENHOUSE EMISSIONS

• Earth Summit in 1992 international agreement
  that climate change must be prevented, but there
  was little action.
• Kyoto Protocol 0ver 100 countries. Countries
  must reduce emissions of six greenhouse gases by
  5 by 2012.
• USA biggest emitter (25 of global emissions)
  refused to sign.
• Carbon emissions need to be reduced by 70-80,

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INTERNATIONAL CO-OPERATION
KYOTO PROTOCOL (1997)
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INTERNATIONAL CO-OPERATION
KYOTO PROTOCOL (1997) over 50 developed
countries pledged to cut greenhouse gas
emissions gases included carbon dioxide CO2
methane CH4 hydrofluorocarbons
HFCs perfluorocarbons PFCs sulphur
hexafluoride SF6 some countries agreed to
make larger cuts developing countries were
not required to cut emissions the US didnt
sign up it would have significantly affected
their economy
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INTERNATIONAL CO-OPERATION
KYOTO PROTOCOL (1997) over 50 developed
countries pledged to cut greenhouse gas
emissions gases included carbon dioxide CO2
methane CH4 hydrofluorocarbons
HFCs perfluorocarbons PFCs sulphur
hexafluoride SF6 some countries agreed to
make larger cuts developing countries were
not required to cut emissions the US didnt
sign up it would have significantly affected
their economy But... Many experts say that the
protocol is futile without US support as they
are the worlds largest emitter of greenhouse
gases. Countries such as India and China are
going through great industrial change and they
do not have to cut emissions. Cuts werent big
enough according to many scientists, who say
that a 60 cut is required to avoid the risks of
global warming.
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EU STRATEGY

• In 2007 the EU agreed a strategy to fight
  against global warming.
• The deal set the following targets to be reached
  by 2020
• 20 of energy used in the EU will come from
  renewable sources.
• 10 of transport fuels will come from biofuels.
• EU greenhouse emissions will be reduced to 20
  below 1990 levels.

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THE GREENHOUSE EFFECT
What can chemists do to minimise climate change
from global warming? provide scientific
evidence to governments to confirm it is taking
place monitor progress against initiatives
such as the Kyoto protocol investigate
solutions to environmental problems
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GOVERNMENTS LISTEN TO SCIENTISTS

• Politicians are now slowly believing what
  scientists have been saying for years Human
  activity is contributing to global warming.
• Politicians are now looking for measures to
  reduce carbon emissions.
• Kyoto Protocol and EU initiatives prove
  governments are listening.

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QUESTIONS

• List three consequences of global warming for the
  Earth.
• Petrol contains a mixture of hydrocarbons,
  including isomers of C8H18.
• Write a balanced equation for the complete
  combustion of C8H18 (assume petrol contains just
  this).
• Calculate the reduction in CO2 emission from a
  car per km in 2012 (130g CO2 per km) compared
  with 2005 (162g CO2 per km) by volume.

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LEARNING OUTCOMES

• Outline how chemists investigate solutions to
  environmental problems, such as carbon capture
  and storage (CCS).
• Understand the removal of waste carbon dioxide
  as a liquid injected deep in the oceans.
• Outline carbon storage in deep geological
  formations, by reaction with metal oxides to form
  stable carbonate minerals.

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CAPTURE AND STORAGE OF CO2 BENEATH THE NORTH SEA
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CARBON DOXIDE CAPTURE STORAGE
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CARBON DOXIDE CAPTURE STORAGE
What is it? CO2 is collected from
industrial processes and power generation
it is separated and purified it is then
transported to a suitable long-term storage site
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CARBON DOXIDE CAPTURE STORAGE
What is it? CO2 is collected from
industrial processes and power generation
it is separated and purified it is then
transported to a suitable long-term storage
site Storage possibilities gaseous
storage in deep geological formations
liquid storage in the ocean solid storage
by reaction as stable carbonates
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CARBON DOXIDE CAPTURE STORAGE
What is it? CO2 is collected from
industrial processes and power generation
it is separated and purified it is then
transported to a suitable long-term storage
site Storage possibilities gaseous
storage in deep geological formations
liquid storage in the ocean solid storage
by reaction as stable carbonates How can it
help? could reduce CO2 emissions from
power stations by 80 could be used to
store CO2 emitted from fermentation processes
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STORAGE AS CARBONATES

• Mineral storage aims to store carbon in stable
  minerals. That is to react CO2 with metal
  oxides to produce stable carbonates. This is how
  limestone rock has been produced.
• For example CaO CO2 CaCO3
• MgO CO2 MgCO3
• The process is very slow and much energy is
  needed to increase the rate of reaction.
• More research is needed if mineral storage is to
  become a viable form of CSS.

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• What is mineral storage and what are the current
  problems with its attempted use?