1. 2.4.1 The Greenhouse effect – global warming
2.4.2 Climate Change
2.4.3 Solutions to the greenhouse effect
2.4.4 The Ozone layer
2.4.5 Ozone depletion
2.4.6 Controlling Air pollution

2. 2.4.1 The Greenhouse effect – global warming
• Explain that infrared radiation is absorbed by C=O, O–H and C– H 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.

3. GREENHOUSE GASES CARBON DIOXIDE CO2 contains C = O bonds
WATER VAPOUR H2O contains O - H bonds
METHANE CH4 contains C - H bonds
The ‘Greenhouse Effect’ of a given gas is dependent on its...
• atmospheric concentration
• ability to absorb infrared radiation

4. 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.

5. 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.

6. 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

7. Bending in a carbon dioxide molecule
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

8. An infra red spectrum of atmospheric air
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
It is the absorption of infra red radiation by atmospheric gases such as methane, carbon dioxide and water vapour that contributes to global warming.
H2O
CO2
CO2
H2O

9. THE GREENHOUSE EFFECT energy from the sun is in the
ultra violet, visible and infra
red regions

10. THE GREENHOUSE EFFECT energy from the sun is in the
ultra violet, visible and infra
red regions
47% reaches the earth

11. 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

12. 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

13. 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

14. 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

15. 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

16. THE GREENHOUSE EFFECT Summary
• energy from the sun is in the ultra violet, visible and infra red regions
• the earth is warmed up by the energy
• radiation re-emitted from the earth is in the infra red region
• 70% of the radiation (between 7000nm and 12500nm) returns to space
• greenhouse gases absorb the remainder
Gas wavelength of radiation adsorbed / nm CO
H2O and above 17000
• they can return this energy to earth to keep it warm

17. The greenhouse effect is a natural process
Task to complete : Page Questions 1,2,3

18. Phet animations – greenhouse effect
Molecules and Light

19. 2.4.2 Climate Change
• 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 as the Kyoto protocol.

20. THE GREENHOUSE EFFECT Problems
An increase in the concentration of greenhouse gases leads to climate change / global warming.

21. THE GREENHOUSE EFFECT Problems
An increase in the concentration of greenhouse gases leads to climate change / global warming.
Possible
Effects

22. THE GREENHOUSE EFFECT Problems
An increase in the concentration of greenhouse gases leads to climate change / global warming.
Possible Effects
• higher temperatures
• melting ice caps
• rise in sea levels
• flooding of low-lying lands
• changes in crop patterns
• deserts move north
• change in food webs
• extinction of some species

23. INTERNATIONAL CO-OPERATION
KYOTO PROTOCOL (1997)

24. INTERNATIONAL CO-OPERATION
KYOTO PROTOCOL (1997)
• over 50 developed countries pledged to cut greenhouse gas emissions
• gases included carbon dioxide CO2
methane CH4
hydrofluorocarbons HFC’s
perfluorocarbons PFC’s
sulphur hexafluoride SF6
• some countries agreed to make larger cuts
• developing countries were not required to cut emissions
• the US didn’t sign up; it would have significantly affected their economy

25. INTERNATIONAL CO-OPERATION
KYOTO PROTOCOL (1997)
• over 50 developed countries pledged to cut greenhouse gas emissions
• gases included carbon dioxide CO2
methane CH4
hydrofluorocarbons HFC’s
perfluorocarbons PFC’s
sulphur hexafluoride SF6
• some countries agreed to make larger cuts
• developing countries were not required to cut emissions
• the US didn’t 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 world’s 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 weren’t big enough according to many scientists, who say that a 60% cut is required to avoid the risks of global warming.

26. – it means changed weather patterns.
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
Task to complete : Page Questions 1,2
Unfortunately some people still think that global warming simply means that we will have warmer weather
– it means changed weather patterns.

27. 2.4.3 Solutions to the greenhouse effect
Outline how chemists investigate solutions to problems such as global warming such as carbon capture and storage.
Understand the removal of waste carbon dioxide as a liquid injected deep in the oceans.
Outline carbon dioxide storage in deep geological formations by reaction with metal oxides to form stable carbonate minerals.

28. CARBON DOXIDE CAPTURE & STORAGE
• 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.

29. 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

30. 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
• reaction with metal oxides to form stable carbonate minerals.
MgO(g) CO2(g) —> MgCO3(s)
CaO(g) CO2(g) —> CaCO3(s)

31. 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

32. 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

33. CARBON DOXIDE CAPTURE & STORAGE
CO2 in geological structures is actually a naturally occurring phenomenon
• CO2 is pumped deep underground
• it is compressed by the higher pressures
• it becomes a liquid, which is trapped between the grains of rock
• impermeable rock prevents the CO2 rising back to the surface
• drilling for CO2 can be used for enhanced oil or gas recovery
Over time CO2 can react with the minerals in the rock, forming new minerals and providing increased storage security.

34. Capture and storage of CO2 beneath the North Sea
Task to complete : Page Questions 1,2

35. 2.4.4 The Ozone layer 2.4.5 Ozone depletion
• Explain that ozone is continuously being formed and broken down in the stratosphere by ultraviolet radiation.
• Describe, using equilibria, how the ozone concentration is maintained in the ozone layer, including the role of ultraviolet radiation.
• Outline the role of ozone in the absorption of harmful ultraviolet radiation and the resulting benefit for life on Earth.
2.4.5 Ozone depletion
• Understand that radicals from CFCs and NOx may catalyse the breakdown of ozone.
• Explain that apparent benefits may be offset by unexpected and detrimental side effects.
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This document may have been altered from the original

36. DEPLETION OF THE OZONE LAYER
Although ozone is a reactive and poisonous gas, it protects us from harmful UV radiation which would affect life on earth. UV radiation can cause skin cancer.

37. Ozone in the atmosphere

38. Absorption of UV radiation by the ozone layer

39. DEPLETION OF THE OZONE LAYER
Although ozone is a reactive and poisonous gas, it protects us from harmful UV radiation which would affect life on earth. UV radiation can cause skin cancer.
Ozone in the stratosphere 2O3 —> 3O2
breaks down naturally
Ozone (trioxygen) can break up O3 —> O• O2
to give ordinary oxygen and an
oxygen radical

40. DEPLETION OF THE OZONE LAYER
Although ozone is a reactive and poisonous gas, it protects us from harmful UV radiation which would affect life on earth. UV radiation can cause skin cancer.
Ozone in the stratosphere 2O3 —> 3O2
breaks down naturally
Ozone (trioxygen) can break up O3 —> O• O2
to give ordinary oxygen and an
oxygen radical
Ultra violet light can supply the energy for the process. That is why the ozone layer is important as it protects us from the harmful rays.
BUT
breakdown is easier in the presence of chlorofluorocarbons (CFC's)

41. DEPLETION OF THE OZONE LAYER
EFFECT OF CFC’S
There is a series of complex reactions but the basic process is :-
CFC's break down in the presence CCl2F2 —> Cl• CClF2
of UV light to form chlorine radicals
chlorine radicals react with ozone O Cl• —> ClO• O2
chlorine radicals are regenerated ClO• O —> O Cl•
Overall chlorine radicals are not used up so a small amount
of CFC's can destroy thousands of ozone molecules
before the termination stage.

42. DEPLETION OF THE OZONE LAYER
OXIDES OF NITROGEN NOx
Oxides of nitrogen, NOx, formed during thunderstorms or by aircraft break down to give NO (nitrogen monoxide) which also catalyses the breakdown of ozone.
nitrogen monoxide reacts with ozone O NO —> NO O2
nitrogen monoxide is regenerated NO O —> O NO
Tasks to complete :
Page Questions 1,2
Page Questions 1,2,3

43. 2.4.6 Controlling Air pollution
• Explain the formation of carbon monoxide, oxides of nitrogen and unburnt hydrocarbons from the internal combustion engine.
• State environmental concerns relating to the toxicity of these molecules and their contribution to low-level ozone and photochemical smog.
• Outline how a catalytic converter decreases toxic emissions via adsorption, chemical reaction and desorption.
• Outline the use of infrared spectroscopy in monitoring air pollution.

44. POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES
POLLUTANTS
POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES
Carbon monoxide CO
Origin • incomplete combustion of hydrocarbons in petrol
because not enough oxygen was present
Effect • poisonous
• combines with haemoglobin in blood
• prevents oxygen being carried to cells
Process C8H18(g) ½O2(g) —> 8CO(g) H2O(l)

45. POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES
POLLUTANTS
POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES
Oxides of nitrogen NOx - NO, N2O and NO2
Origin • combination of atmospheric nitrogen and
oxygen under high temperature
Effect • aids formation of photochemical smog which is
irritating to eyes, nose, throat
• aids formation of low level ozone which affects plants and is irritating to eyes, nose and throat
Process sunlight breaks oxides NO2 —> NO + O
ozone is produced O + O2 —> O3

46. POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES
POLLUTANTS
POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES
Unburnt hydrocarbons CxHy
Origin • hydrocarbons that have not undergone combustion
Effect • toxic and carcinogenic (cause cancer)

47. POLLUTANTS POLLUTANT FORMATION Nitrogen combines with oxygen
N2(g) + O2(g) —> 2NO(g)
Nitrogen monoxide is oxidised
2NO(g) + O2(g) —> 2NO2(g)
Incomplete hydrocarbon combustion
C8H18(g) ½O2(g) —> 8CO(g) H2O(l)

48. POLLUTANTS POLLUTANT REMOVAL Oxidation of carbon monoxide
2CO(g) + O2(g) —> 2CO2(g)
Removal of NO and CO
2CO(g) + 2NO(g) —> N2(g) + 2CO2(g)
Aiding complete hydrocarbon combustion
C8H18(g) ½O2(g) —> 8CO2(g) H2O(l)

49. CATALYTIC CONVERTERS REMOVAL OF NOx and CO • CO is converted to CO2
• NOx are converted to N2
2NO(g) CO(g) —> N2(g) CO2(g)

50. CATALYTIC CONVERTERS REMOVAL OF NOx and CO • CO is converted to CO2
• NOx are converted to N2
2NO(g) CO(g) —> N2(g) CO2(g)
• Unburnt hydrocarbons converted to CO2 and H2O
C8H18(g) ½O2(g) —> 8CO2(g) H2O(l)

51. CATALYTIC CONVERTERS REMOVAL OF NOx and CO • CO is converted to CO2
• NOx are converted to N2
2NO(g) CO(g) —> N2(g) CO2(g)
• Unburnt hydrocarbons converted to CO2 and H2O
C8H18(g) ½O2(g) —> 8CO2(g) H2O(l)
• catalysts are rare metals - RHODIUM, PALLADIUM
• metals are finely divided for a greater surface area
- this provides more active sites

52. Emissions of nitrogen oxides
A three-way catalytic converter

53. CATALYTIC CONVERTERS
STAGES OF OPERATION

54. CATALYTIC CONVERTERS STAGES OF OPERATION
Adsorption • NO and CO seek out active sites on the surface
• they bond with surface
• weakens the bonds in the gas molecules
• makes a subsequent reaction easier

55. CATALYTIC CONVERTERS STAGES OF OPERATION
Reaction • being held on the surface increases chance of
favourable collisions
• bonds break and re-arrange

56. CATALYTIC CONVERTERS STAGES OF OPERATION
Desorption • products are released from the active sites

57. CATALYTIC CONVERTERS STAGES OF OPERATION
Adsorption Reaction Desorption

58. CATALYTIC CONVERTERS STAGES OF OPERATION
Adsorption • NO and CO seek out active sites on the surface
• they bond with surface
• weakens the bonds in the gas molecules
• makes a subsequent reaction easier
Reaction • being held on the surface increases chance of
favourable collisions
• bonds break and re-arrange
Desorption • products are released from the active sites

59. Fractional distillation 
Because fractions have different boiling points 
Decane 
Formula must be skeletal
AND must not include any symbol, e.g. CH3

60. Decane has more surface contact OR branched chains have less surface contact 
Decane has more van der Waals’ forces
OR branched chains have fewer van der Waals’ forces 
Branched chains have more efficient combustion
OR decane has less efficient combustion

61. C10H ½O2  10CO2 + 11H2O
N2 + O2  2NO 

62. Species with an unpaired electron 
catalyst 

63. O + O2  O3
OR O reacts with O2 to make ozone
OR the reaction is reversible 
Rate of formation of ozone is the same as rate of decomposition 
absorbs (harmful) UV 

68. Infrared (radiation absorbed) 
by (C–H) bond vibration 
Greater concentration of carbon dioxide
OR more carbon dioxide is being made 

69. Developing carbon capture AND storage  One example of CCS 
Second example of CCS 
Provide evidence to governments OR international conferences (e.g. Kyoto) OR reports to United Nations etc 
Educating society OR writing in journals OR producing documentaries OR writing books OR making posters 
Monitoring atmospheric changes 
Develop alternative energy sources 
One example of an alternative energy source e.g. develop fuel cells OR developing solar power OR fuels that do not produce CO2 
(Develop) more efficient engines for transport
OR lean burn engines OR hybrid engines OR electric cars 
Find uses for carbon dioxide OR named use:
e.g. dry cleaning OR making decaffeinated coffee OR blowing agent OR fizzy drinks, etc 

71. There are times when CO2 has a high concentration and the temperature is also highOR
There are times when CO2 has a low concentration and the temperature is low 
It is impossible to measure with certainty the average temperature years ago 
There are other gases that may cause a greenhouse effect
There are other factors that may cause a greenhouse effect 
There are very few anomalous results 