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

2.4.1 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.

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

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.

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.

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

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

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

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

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

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

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

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

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

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

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 CO2 12500 - 17000 H2O 4500 - 7000 and above 17000 • they can return this energy to earth to keep it warm

The greenhouse effect is a natural process Task to complete : 2.4.1- Page 221 - Questions 1,2,3

Phet animations – greenhouse effect Molecules and Light

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.

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

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

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

INTERNATIONAL CO-OPERATION KYOTO PROTOCOL (1997)

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

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.

– 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 : 2.4.2- Page 223 - Questions 1,2 Unfortunately some people still think that global warming simply means that we will have warmer weather – it means changed weather patterns.

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.

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.

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

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)

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

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

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.

Capture and storage of CO2 beneath the North Sea Task to complete : 2.4.3- Page 225 - Questions 1,2

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. © Pearson Education Ltd 2008 This document may have been altered from the original

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 atmosphere

Absorption of UV radiation by the ozone layer

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

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)

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 O3 + Cl• —> ClO• + O2 chlorine radicals are regenerated ClO• + O —> O2 + 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.

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 O3 + NO —> NO2 + O2 nitrogen monoxide is regenerated NO2 + O —> O2 + NO Tasks to complete : 2.4.4- Page 227 - Questions 1,2 2.4.5- Page 229 - Questions 1,2,3

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.

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) + 8½O2(g) —> 8CO(g) + 9H2O(l)

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

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)

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) + 8½O2(g) —> 8CO(g) + 9H2O(l)

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) + 12½O2(g) —> 8CO2(g) + 9H2O(l)

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

CATALYTIC CONVERTERS REMOVAL OF NOx and CO • CO is converted to CO2 • NOx are converted to N2 2NO(g) + 2CO(g) —> N2(g) + 2CO2(g) • Unburnt hydrocarbons converted to CO2 and H2O C8H18(g) + 12½O2(g) —> 8CO2(g) + 9H2O(l)

CATALYTIC CONVERTERS REMOVAL OF NOx and CO • CO is converted to CO2 • NOx are converted to N2 2NO(g) + 2CO(g) —> N2(g) + 2CO2(g) • Unburnt hydrocarbons converted to CO2 and H2O C8H18(g) + 12½O2(g) —> 8CO2(g) + 9H2O(l) • catalysts are rare metals - RHODIUM, PALLADIUM • metals are finely divided for a greater surface area - this provides more active sites

Emissions of nitrogen oxides A three-way catalytic converter

CATALYTIC CONVERTERS STAGES OF OPERATION

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

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

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

CATALYTIC CONVERTERS STAGES OF OPERATION Adsorption Reaction Desorption

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

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

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

C10H22 + 15½O2  10CO2 + 11H2O N2 + O2  2NO 

Species with an unpaired electron  catalyst 

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 

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

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 

There are times when CO2 has a high concentration and the temperature is also high OR 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 