GREEN CHEMISTRY What is it? encourages environmentally conscious behaviour reduces and prevents pollution reduces the destruction of the planet

CONTENTS Greenhouse gases Greenhouse effect Ozone layer Pollutants Catalytic converters CHEMISTRY OF THE AIR

GREENHOUSE GASES Definition :  A greenhouse gas traps/absorbs/reflects IR (radiation) / heat  re-radiating from the earth Examples of green house gases: CO 2, H 2 O, Methane

CARBON DIOXIDECO 2 containsC = O bonds WATER VAPOURH 2 OcontainsO - H bonds METHANECH 4 containsC - 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

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

GREENHOUSE GASES INFRA RED 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. H2OH2O H2OH2O CO 2

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 radiation re-emitted from the earth is in the infra red region 47% reaches the earth

THE GREENHOUSE EFFECT energy from the sun is in the ultra violet, visible and infra red regions radiation re-emitted from the earth is in the infra red region 70% of the radiation returns to space 47% reaches the earth

THE GREENHOUSE EFFECT energy from the sun is in the ultra violet, visible and infra red regions radiation re-emitted from the earth is in the infra red region 70% of the radiation returns to space 47% reaches the earth greenhouse gases absorb the remainder

THE GREENHOUSE EFFECT energy from the sun is in the ultra violet, visible and infra red regions radiation re-emitted from the earth is in the infra red region 70% of the radiation returns to space 47% reaches the earth 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 radiation re-emitted from the earth is in the infra red region 70% of the radiation returns to space greenhouse gases absorb the remainder 47% reaches the earth 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 CO H 2 O and above they can return this energy to earth to keep it warm

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

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

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 plus CARBON CAPTURE AND STORAGE (CCS) removal of waste carbon dioxide as a liquid injected deep in the oceans storage underground in deep geological formations reaction with metal oxides to form stable carbonate minerals. MgO(g) + CO 2 (g) —> MgCO 3 (s) or CaO(g) + CO 2 (g) —> CaCO 3 (s)

CARBON DOXIDE CAPTURE & STORAGE

What is it? CO 2 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? CO 2 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

CARBON DOXIDE CAPTURE & STORAGE What is it? CO 2 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 CO 2 emissions from power stations by 80% could be used to store CO 2 emitted from fermentation processes

CARBON DOXIDE CAPTURE & STORAGE What is it? CO 2 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 CO 2 emissions from power stations by 80% could be used to store CO 2 emitted from fermentation processes

CARBON DOXIDE CAPTURE & STORAGE CO 2 in geological structures is actually a naturally occurring phenomenon CO 2 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 CO 2 rising back to the surface drilling for CO 2 can be used for enhanced oil or gas recovery Over time CO 2 can react with the minerals in the rock, forming new minerals and providing increased storage security.

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.

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 stratosphere2O 3 —> 3O 2 breaks down naturally Ozone (trioxygen) can break upO 3 —> O + O 2 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 stratosphere2O 3 —> 3O 2 breaks down naturally Ozone (trioxygen) can break upO 3 —> O + O 2 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 REACTIONS OF CFC’S CFC's break down in the presence of UV light to form chlorine radicals CC l 2 F 2 —> C l + CC l F 2 chlorine radicals react with ozone chlorine radicals are regenerated

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. NO() + O 3  ()NO 2 + O 2 NO 2 + O 3  NO + 2O Overoll : 2O 3  3O 2  1 NO molecule can break large number of ozone molecules as NO radical is reformed

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 ProcessC 8 H 18 (g) + 8½O 2 (g) —> 8CO(g) + 9H 2 O(l)

POLLUTANTS POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES Oxides of nitrogen NOx - NO, N 2 O and NO 2 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 Processsunlight breaks oxidesNO 2 —> NO + O ozone is produced O + O 2 —> O 3

POLLUTANTS POLLUTANT GASES FROM INTERNAL COMBUSTION ENGINES Unburnt hydrocarbons C x H y Origin hydrocarbons that have not undergone combustion Effect toxic and carcinogenic (cause cancer)

POLLUTANTS POLLUTANT FORMATION Nitrogen combines with oxygen N 2 (g) + O 2 (g) —> 2NO(g) Nitrogen monoxide is oxidised 2NO(g) + O 2 (g) —> 2NO 2 (g) Incomplete hydrocarbon combustion C 8 H 18 (g) + 8½O 2 (g) —> 8CO(g) + 9H 2 O(l)

POLLUTANTS POLLUTANT REMOVAL Oxidation of carbon monoxide 2CO(g) + O 2 (g) —> 2CO 2 (g) Removal of NO and CO 2CO(g) + 2NO(g) —> N 2 (g) + 2CO 2 (g) Aiding complete hydrocarbon combustion C 8 H 18 (g) + 12½O 2 (g) —> 8CO 2 (g) + 9H 2 O(l)

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

CATALYTIC CONVERTERS REMOVAL OF NOx and CO CO is converted to CO 2 NOx are converted to N 2 2NO(g) + 2CO(g) —> N 2 (g) + 2CO 2 (g) Unburnt hydrocarbons converted to CO 2 and H 2 O C 8 H 18 (g) + 12½O 2 (g) —> 8CO 2 (g) + 9H 2 O(l)

CATALYTIC CONVERTERS REMOVAL OF NOx and CO CO is converted to CO 2 NOx are converted to N 2 2NO(g) + 2CO(g) —> N 2 (g) + 2CO 2 (g) Unburnt hydrocarbons converted to CO 2 and H 2 O C 8 H 18 (g) + 12½O 2 (g) —> 8CO 2 (g) + 9H 2 O(l) catalysts are rare metals - RHODIUM, PALLADIUM metals are finely divided for a greater surface area - this provides more active sites

GREEN CHEMISTRY What is it? encourages environmentally conscious behaviour reduces and prevents pollution reduces the destruction of the planet Basics better to prevent waste than to treat it afterwards aim for maximum atom economy use processes which require fewer chemicals don’t make products that are toxic to human health don’t make products that are toxic to the environment reduce the energy requirements of processes use alternative energy resources use renewable raw materials, not finite resources use catalysts where possible waste products should be designed to be biodegradable reduce the risk of explosions and fires

RECYCLING Definition“Recovering resources by collecting, separating, and processing scrap materials and using them as raw materials for manufacturing new products.”

RECYCLING Definition“Recovering resources by collecting, separating, and processing scrap materials and using them as raw materials for manufacturing new products.” Why do it? world resources are running out and are non-renewable we need to reduce the waste of valuable resources reduces the expense of disposal reduces expense of making things from raw materials avoids environmental problems posed by waste - landfill sites - greenhouse gases (mainly methane) - destroying habitats - de-forestation leading to climate change and the destruction of ecosystems

RENEWABLE RESOURCES AND ENERGY

Renewable resources can be replenished by natural processes their rate of replenishment is equal or greater than the rate of consumption often do not contribute to global warming often far more environmentally friendly lead to more sustainable use of materials; resources can be used indefinitely

RENEWABLE RESOURCES AND ENERGY Renewable resources can be replenished by natural processes their rate of replenishment is equal or greater than the rate of consumption often do not contribute to global warming often far more environmentally friendly lead to more sustainable use of materials; resources can be used indefinitely Renewable energy plant-based substances such as wood solar energy tidal energy biomass hydro-electric power (HEP) wind power

GREEN CHEMISTRY – EXAMPLES CFC’s Apparent benefits were offset by unexpected side effects.

GREEN CHEMISTRY – EXAMPLES CFC’s Apparent benefits were offset by unexpected side effects. GOOD created in 1928 as a non-toxic, non-flammable refrigerant also used as solvents and in air conditioners low reactivity and volatility

GREEN CHEMISTRY – EXAMPLES CFC’s Apparent benefits were offset by unexpected side effects. GOOD created in 1928 as a non-toxic, non-flammable refrigerant also used as solvents and in air conditioners low reactivity and volatility BAD UV light in the upper atmosphere easily breaks the C-C l bonds free radicals formed speeded up the depletion of the ozone layer

GREEN CHEMISTRY – EXAMPLES CFC’s Apparent benefits were offset by unexpected side effects. GOOD created in 1928 as a non-toxic, non-flammable refrigerant also used as solvents and in air conditioners low reactivity and volatility BAD UV light in the upper atmosphere easily breaks the C-C l bonds free radicals formed speeded up the depletion of the ozone layer CFC's break down in the presence of UV light to form chlorine radicalsCC l 2 F 2 —> C l + CC l F 2 chlorine radicals react with ozoneO 3 + C l —> C l O + O 2 chlorine radicals are regeneratedC l O + O —> O 2 + C l Overall, chlorine radicals are not used up so a small amount of CFC's can destroy thousands of ozone molecules before the termination stage.

GREEN CHEMISTRY – EXAMPLES CFC’s Apparent benefits were offset by unexpected side effects. GOOD created in 1928 as a non-toxic, non-flammable refrigerant also used as solvents and in air conditioners low reactivity and volatility BAD UV light in the upper atmosphere easily breaks the C-C l bonds free radicals formed speeded up the depletion of the ozone layer CFC's break down in the presence of UV light to form chlorine radicalsCC l 2 F 2 —> C l + CC l F 2 chlorine radicals react with ozoneO 3 + C l —> C l O + O 2 chlorine radicals are regeneratedC l O + O —> O 2 + C l Overall, chlorine radicals are not used up so a small amount of CFC's can destroy thousands of ozone molecules before the termination stage.

GREEN CHEMISTRY – EXAMPLES BIOFUELS fuels made from a living things or the waste produced by them renewable and potentially carbon neutral.

GREEN CHEMISTRY – EXAMPLES BIOFUELS fuels made from a living things or the waste produced by them renewable and potentially carbon neutral. Carbon neutral refers to “an activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere”. Ethanol is a biofuel.

GREEN CHEMISTRY – EXAMPLES BIOFUELS fuels made from a living things or the waste produced by them renewable and potentially carbon neutral. Carbon neutral refers to “an activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere”. Ethanol is a biofuel.ETHANOL GOOD

GREEN CHEMISTRY – EXAMPLES BIOFUELS fuels made from a living things or the waste produced by them renewable and potentially carbon neutral. Carbon neutral refers to “an activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere”. Ethanol is a biofuel.ETHANOL GOOD bio-ethanol is made from crops (corn and sugar cane) takes in carbon as carbon dioxide in the atmosphere when burnt, it returns CO 2 to the atmosphere appears to be carbon neutral

GREEN CHEMISTRY – EXAMPLES BIOFUELS fuels made from a living things or the waste produced by them renewable and potentially carbon neutral. Carbon neutral refers to “an activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere”. Ethanol is a biofuel.ETHANOL GOOD bio-ethanol is made from crops (corn and sugar cane) takes in carbon as carbon dioxide in the atmosphere when burnt, it returns CO 2 to the atmosphere appears to be carbon neutral BAD

GREEN CHEMISTRY – EXAMPLES BIOFUELS fuels made from a living things or the waste produced by them renewable and potentially carbon neutral. Carbon neutral refers to “an activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere”. Ethanol is a biofuel.ETHANOL GOOD bio-ethanol is made from crops (corn and sugar cane) takes in carbon as carbon dioxide in the atmosphere when burnt, it returns CO 2 to the atmosphere appears to be carbon neutral BAD energy is required to - plant and harvest - convert plants to ethanol fertiliser and pesticides used are pollutants crops compete for land with… crops / animals / forests could destroy natural habitats and reduce biodiversity

GREEN CHEMISTRY – EXAMPLES PLASTICS & POLYMERS Plastics have made life much easier.

GREEN CHEMISTRY – EXAMPLES PLASTICS & POLYMERS Plastics have made life much easier. GOOD

GREEN CHEMISTRY – EXAMPLES PLASTICS & POLYMERS Plastics have made life much easier. GOOD many are chemically inert non-toxic waterproof easy to mould non-biodegradable lightweight

GREEN CHEMISTRY – EXAMPLES PLASTICS & POLYMERS Plastics have made life much easier. GOOD many are chemically inert non-toxic waterproof easy to mould non-biodegradable lightweight BAD

GREEN CHEMISTRY – EXAMPLES PLASTICS & POLYMERS Plastics have made life much easier. GOOD many are chemically inert non-toxic waterproof easy to mould non-biodegradable lightweight BAD made from crude oil which is a finite resource non-biodegradable so take hundreds of years to decompose can form toxic products during incineration a lot of energy is used in their formation disposal in landfill sites is- a waste of resources - environmentally unsound - takes up valuable space

GREEN CHEMISTRY – EXAMPLES CATALYSTS can be used to lower the energy required for a reaction to take place can reduce the CO 2 emissions from burning of fossil fuels can give a better atom economy

SOME MORE THINGS YOU SHOULD KNOW

Anthropogenic: results from human activities, e.g. burning fossil fuels and deforestation. These increase levels of CO2, methane and other gases over relatively short timescales. Natural climate change: natural processes such as dissolving of CO2 in sea water or formation of carbonates in rocks over hundreds of years. Volcanic eruptions can also cause climate change. Carbon neutral : a process that gives out as much CO2 as it takes in The fuel petrol is definitely not carbon neutral - releases CO2 into atmosphere which was trapped in the earth millions of years ago. Hydrogen gas can be carbon neutral. Carbon footprint : a measure of the impact on environment from how much greenhouse gas is produced. (Measured in CO2) Catalysts : enable a reaction to go under lower temperatures and pressures to save energy. Catalysts need to be cheap, very active and produce no by- products

Crude oil vs Bio fuels  Biofuels are renewable but cude oil is not renewable Consequences of global warming  Sea level rize / flooding  Melting polar ice caps  Changing sea currents  Changing weather patterns Whether hydrogen or ammonia can currently be considered to be long term replacements for fossil fuels?? No because hydrogen is obtained from fossil fuels (and ammonia from hydrogen) OR Yes because hydrogen can be obtained by electrolysis of water

Using high pressure when recycling ??  (High cost of) energy needed (togenerate the pressure)  (High cost of) construction/maintenance of the equipment  (High cost of) the equipmentrequired to withstand / contain the high pressure fules should have these qualities ?? Less Cost / Ease of Production Easy to Store Easy to Transport Renewable Less environmental effect

Carbon monoxide from incomplete combustion of fuels  toxic to breathe Sulfur dioxide and nitrogen oxide (from industrial and vehicular exhaust  causes of acid rain Chlorofluorocarbon (CFC) used as aerosol / propellant / spray cans refrigerant OR (degreasing) solvent OR fire retardant  causes destruction of the ozone layer)

Some Green house gases : * Water vapour (H 2 O) * Carbon dioxide (CO 2 )  (fossil fuel burning and greenhouse gas), * Methane (CH 4 )  (cow farming, landfill emissions and natural sources, greenhouse gas) * Nitrous oxide (N 2 O) * Ozone (which is bad at low altitudes and does not survive to replenish the high altitude ozone layer which protects us from UV light)

SOME MORE THINGS YOU SHOULD DISCUSS AFTER THE ENED OF THE LESSON

a ) demonstrate an understanding that the processes in the chemical industry are being reinvented to make them more sustainable (‘greener’) by: i ) changing to renewable resources ii ) finding alternatives to very hazardous chemicals iii ) discovering catalysts for reactions with higher atom economies, eg the development of methods used to produce ethanoic acid based on catalysts of cobalt, rhodium and iridium iv ) making more efficient use of energy, eg the use of microwave energy to heat reactions in the pharmaceutical industry v ) reducing waste and preventing pollution of the environment

b) discuss the relative effects of different greenhouse gases as absorbers of IR and hence on global warming c ) discuss the difference between anthropogenic and natural climate change over hundreds of thousands of years d ) demonstrate understanding of the terms ‘carbon neutrality’ and ‘carbon footprint’ e ) apply the concept of carbon neutrality to different fuels, such as petrol, bio-ethanol and hydrogen f ) discuss and explain, including the mechanisms for the reactions, the science community’s reasons for recommending that CFCs are no longer used due to their damaging effect on the ozone layer.