KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING

2008 2008 SPECIFICATIONSSPECIFICATIONS

GREENGREEN

CHEMISTRYCHEMISTRY

INTRODUCTION

This Powerpoint show is one of several produced to help students understand selected topics at AS and A2 level Chemistry. It is based on the requirements of the AQA and OCR specifications but is suitable for other examination boards.

Individual students may use the material at home for revision purposes or it may be used for classroom teaching with an interactive white board.

Accompanying notes on this, and the full range of AS and A2 topics, are available from the KNOCKHARDY SCIENCE WEBSITE at...

www.knockhardy.org.uk/sci.htm

Navigation is achieved by...

either clicking on the grey arrows at the foot of each page

or using the left and right arrow keys on the keyboard

KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING

GREEN CHEMISTRYGREEN CHEMISTRY

GREEN CHEMISTRYGREEN CHEMISTRY

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

GREEN CHEMISTRYGREEN 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

RECYCLINGRECYCLING

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

RECYCLINGRECYCLING

Definition “Recovering resources by collecting, separating, andprocessing scrap materials and using them as rawmaterials 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 ENERGYRENEWABLE RESOURCES AND ENERGY

RENEWABLE RESOURCES AND ENERGYRENEWABLE RESOURCES AND ENERGY

Renewableresources • 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 ENERGYRENEWABLE RESOURCES AND ENERGY

Renewableresources • 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

Renewableenergy • plant-based substances such as wood

• solar energy• tidal energy• biomass• hydro-electric power (HEP)• wind power

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

CFC’sCFC’sApparent benefits were offset by unexpected side effects.

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

CFC’sCFC’sApparent 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 – EXAMPLESGREEN CHEMISTRY – EXAMPLES

CFC’sCFC’sApparent 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-Cl bonds• free radicals formed speeded up the depletion of the ozone layer

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

CFC’sCFC’sApparent 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-Cl bonds• free radicals formed speeded up the depletion of the ozone layer

CFC's break down in the presence ofUV light to form chlorine radicals CCl2F2 —> Cl• + •CClF2

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 candestroy thousands of ozone molecules before the termination stage.

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

CFC’sCFC’sApparent 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-Cl bonds• free radicals formed speeded up the depletion of the ozone layer

CFC's break down in the presence ofUV light to form chlorine radicals CCl2F2 —> Cl• + •CClF2

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 candestroy thousands of ozone molecules before the termination stage.

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

BIOFUELSBIOFUELS• fuels made from a living things or the waste produced by them• renewable and potentially carbon neutral.

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

BIOFUELSBIOFUELS• 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 – EXAMPLESGREEN CHEMISTRY – EXAMPLES

BIOFUELSBIOFUELS• 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.

ETHANOLETHANOL

GOOD

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

BIOFUELSBIOFUELS• 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.

ETHANOLETHANOL

GOOD • bio-ethanol is made from crops (corn and sugar cane)• takes in carbon as carbon dioxide in the atmosphere• when burnt, it returns CO2 to the atmosphere• appears to be carbon neutral

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

BIOFUELSBIOFUELS• 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.

ETHANOLETHANOL

GOOD • bio-ethanol is made from crops (corn and sugar cane)• takes in carbon as carbon dioxide in the atmosphere• when burnt, it returns CO2 to the atmosphere• appears to be carbon neutral

BAD

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

BIOFUELSBIOFUELS• 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.

ETHANOLETHANOL

GOOD • bio-ethanol is made from crops (corn and sugar cane)• takes in carbon as carbon dioxide in the atmosphere• when burnt, it returns CO2 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 – EXAMPLESGREEN CHEMISTRY – EXAMPLES

PLASTICS & POLYMERSPLASTICS & POLYMERSPlastics have made life much easier.

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

PLASTICS & POLYMERSPLASTICS & POLYMERSPlastics have made life much easier.

GOOD

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

PLASTICS & POLYMERSPLASTICS & POLYMERSPlastics have made life much easier.

GOOD • many are chemically inert• non-toxic• waterproof• easy to mould• non-biodegradable• lightweight

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

PLASTICS & POLYMERSPLASTICS & POLYMERSPlastics have made life much easier.

GOOD • many are chemically inert• non-toxic• waterproof• easy to mould• non-biodegradable• lightweight

BAD

GREEN CHEMISTRY – EXAMPLESGREEN CHEMISTRY – EXAMPLES

PLASTICS & POLYMERSPLASTICS & POLYMERSPlastics 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 – EXAMPLESGREEN CHEMISTRY – EXAMPLES

CATALYSTSCATALYSTS• can be used to lower the energy required for a reaction to take place• can reduce the CO2 emissions from burning of fossil fuels• can give a better atom economy

INTERNATIONAL CO-OPERATIONINTERNATIONAL CO-OPERATION

KYOTO PROTOCOL (1997)KYOTO PROTOCOL (1997)

INTERNATIONAL CO-OPERATIONINTERNATIONAL CO-OPERATION

KYOTO PROTOCOL (1997)KYOTO PROTOCOL (1997)• over 50 developed countries pledged to cut greenhouse gas emissions• gases included carbon dioxide CO2

methane CH4

hydrofluorocarbons HFC’sperfluorocarbons PFC’ssulphur 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-OPERATIONINTERNATIONAL CO-OPERATION

KYOTO PROTOCOL (1997)KYOTO PROTOCOL (1997)• over 50 developed countries pledged to cut greenhouse gas emissions• gases included carbon dioxide CO2

methane CH4

hydrofluorocarbons HFC’sperfluorocarbons PFC’ssulphur 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 greatindustrial 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.

©2009 JONATHAN HOPTON & KNOCKHARDY PUBLISHING©2009 JONATHAN HOPTON & KNOCKHARDY PUBLISHING

THE ENDTHE END

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CHEMISTRYCHEMISTRY