1.1 earth recieves most of its energy in the form of electromagnetic radiation from the sun. Mostly
from the visible reigion of the spectrum, with small amounts from the infrared and ultraviolet
1.1.1 The incoming radiation is realtively unaffected by
the gases in the Earth's atmosphere, and passes
straight through to the Earth's surface.
188.8.131.52 Most infrared radiation emitted by the
earth's surfaces goes back into space.
However, certain gases in the atmosphere
absorb some of this IR. It is then re-emitted
as energy, with some passing back
towards the Earth. This process effectively
traps much of the heat in the lower
184.108.40.206.1 In CO2, a linear molecule, the c-o bond
absorbs IR causing the molecule to vibrate.
Eventually the vibrating molecule emits some
of this energy in the form of radiation. This
can then be absorbed by another
greenhouse gas molecule or at the Earth's
surface. In H2O, the O-H bonds absorb IR, in
methane, the C-H bonds absorb IR.
220.127.116.11.1.1 The greenhouse effect of a gas
depends not only on its concentration in
the atmosphere, but also on its ability to
18.104.22.168.1.1.1 The absorbtion-emission process keeps the heat close to the earth's surface.
1.2 natural process, keeping
our planet at a
temperature capable of
supporting human life.
1.2.1 Human activity is producing more
greenhouse gases, which threaten to
upset this fine natural balance,
resulting in global warming.
1.3 creates an equilibrium. The earth's surface and
atmospheric gases absorb energy at the same
rate as it radiates energy, thus maintaining a
1.4 greenhouse gases
1.4.1 occur naturally in the atmosphere. Water Vapour is the most
abundant of them, with CO2 the next. CO2 is produced by;
volcanic erruptions, respiration of animals. burning or decay of
organic matter, such as plants. The third most abundant is
methane, although present in smaller quantities than CO2,
methane makes a greater contribution to the greenhouse effect
than the same amount of CO2. Methane is: emitted during the
production of coal, natural gas and oil; a product of rotting organic
waste in landfill sites; released from certain animals, especially
cows, as a by-product of digestion; also found in large quantities
trapped in ice like structures under the cold northen seas
1.5 global warming potential
1.5.1 related to the lifetime of a gas in the atmosphere, as well as the ability of the gas to absorb IR.
22.214.171.124 some chloroflourocarbons (CFCs) are much more
efficient at absorbing IR than CO2 but, since
legislation banned the large-scale use of CFCs,
their effect is diminishing.
1.5.2 luckily the atmospheric concentrations of
CFCs and other molecules with a high
GWP have always been much lower than
for CO2 and H2O
2 Climate Change
2.1.1 Alternative fuels
126.96.36.199 wind turbines
188.8.131.52 tidal power
184.108.40.206 solar panels
220.127.116.11 nuclear plants
2.1.2 Carbon Capture and Storage
18.104.22.168 captures CO2 from power stations and stores it away safely, instead of it being released
into the atmosphere. It is an immediate strategy to get rid of waste CO2 gas.
22.214.171.124 underground porous rocks can act as a sponge to store CO2 gas and keep it from leaking away
126.96.36.199 old oil and gas fields are great natural containers for CO2 gas
188.8.131.52 decarbonised fuels
184.108.40.206.1 reduce carbon emissions by about 90%
220.127.116.11.2 CH4 + 2H2O = CO2 + 4H2
18.104.22.168.2.1 the remaining CO2 will then be seperated and
piped offshore to an oilfield which is nearing
the end of its productive life
22.214.171.124.2.2 the hydrogen could be burnt as a truly
clean fuel, and the CO2 could be
captured and stored safely
126.96.36.199.3 could be fitted into existing power stations and petrochemical plants.
188.8.131.52 the UK alone can store an extortionate amount of CO2
184.108.40.206 storage as carbonates (Mineral storage)
220.127.116.11.1 CO2 is reacted with metal oxides to produce stable carbonates (carbonate rocks)
18.104.22.168.1.1 CaO + CO2 = CaCO3
MgO + CO2 = MgCO3
22.214.171.124.2 occurs naturally, for example limestone rocks. natural
reaction is very slow and efforts to increase the rate are
very energy intensive. More research is required if
mineral storage is to become a viable form of CCS
3.1 the ozone layer
3.1.1 good ozone
126.96.36.199 in the stratosphere;
preventing harmful UV
light from reaching the
3.1.2 bad ozone
188.8.131.52 in the troposphere;
air pollutant wuth
harmful effects on the
respiratory system of
3.1.3 found in the stratosphere, filters out the shorter UV wavelengths
(less than 320 nm). These shorter wavelengths would be very
damaging to life.
184.108.40.206 the ozone converts this UV radiation into heat and
consequently, the ozone layer is at a higher temp than other
parts of the upper atmosphere.
3.1.4 the ozone-oxygen cycle
220.127.116.11 ozone is continuously being formed and broken
down in the stratosphere by the action of UV
radiation which occurs in three types.
18.104.22.168.1 UV-a (320-400nm)
22.214.171.124.1.1 reaches the earth's surface, only 5% absorbed by
ozone. less energy than shorter wavelengths and
not as damaging, doesn't cause much concern.
126.96.36.199.2 UV-b (280-320nm)
188.8.131.52.2.1 95% absorbed, can cause sunburn and sometimes
genetic damage, which can result in
skin cancer, if exposure is prolonged
184.108.40.206.2.2 although ozone screens out most of UV-b, some does reach
the Earth's surface. Any decrease in the ozone layer would
allow more UV-b to reach the surface and increase the genetic
damage to living organisms.
220.127.116.11.3 UV-c (200-280nm)
18.104.22.168.3.1 100% absorbed,
entirely screened out
by the ozone layer.
22.214.171.124 O2 + (radiation < 240nm) = 2O
126.96.36.199.1 O2 + O = O3 + heat
188.8.131.52.1.1 O3 + (radiation < 310nm) = O2 + O
184.108.40.206.1.1.1 O2 + O = O3 + heat
220.127.116.11.18.104.22.168 removal of ozone
O3 + O = 2O2
22.214.171.124.126.96.36.199.1 luckily for us, the removal rate
is slow, since the
concentration of O atoms is
3.2 Ozone depletion
3.2.1 it is recognized that most chlorine radicals in the stratosphere are
generated by human activity. This has upset the natural ozone-oxygen
balance, leading to problems in maintaining the protective ozone layer.
Chlorine radicals mainly come from CFCs which can take years to reach
the reach the ozone layer.
188.8.131.52 poisonous gas, emitted due to incomplete combustion of
hydrocarbons/organic compounds, mainly occurs from traffic
pollution, mainly from urban areas. Exists from 1 month before
is oxidised into CO2. serious health implications on humans.
4.1.2 Oxides of Nitrogen
184.108.40.206 air is drawn into the engine cylinder, some of
the N from the air is oxidised by the oxygen
under this high temp process. NO and NO2
are produced, the concentrations of which are
higher in urban areas where traffic levels are
high. NO2 forms low level ozone, and nitric
acid, a contributor to acid rain, nitrogen oxides
are respiratory irritants and effect asthmatics
even in low levels.
4.1.3 Unburnt Hydrocarbons
220.127.116.11 volatile organic compounds are released, usually from
unburnt fuels. Two compounds of particular concern
are benzene and buta-1,3-diene, both of which are
found in petrol in small quantities and are know human
carcinogens. Once released into the atmosphere, the
unburnt HC and NO2 react together to form low-level
ozone, the energy of this reaction is provided by
sunlight. the mechanism involves radicals. low-level
ozone is a serious pollutant, causing breathing
difficulties and increasing susceptibility to infections.
Urban areas are more prone to low level ozone
4.2 Infrared spec is currently being
developed to monitor
4.3 The catalytic converter
4.3.1 oxidation catalyst
18.104.22.168 used on diesel engines to to decrease
emissions of CO and unburnt
hydrocarbons. Combined with
complex filter systems, they also
remove particulate matter and nitrogen
22.214.171.124.1 2CO + O2 = 2CO2
126.96.36.199.1.1 C12H26 + 18.5O2 = 12CO2 + 13H2O
4.3.2 three-way catalyst
188.8.131.52 fitted to petrol engines. In this system, NO reacts
with CO to form the non-toxic gases N and CO2
184.108.40.206.1 2NO + 2CO = N2 + 2CO2
220.127.116.11 provides a surface on which the reaction takes place.
18.104.22.168.1 CO and NO molecules diffuse over the catalytic
surface of the metal. Some of the molecules are
held on to the metal surface by adsorption.
22.214.171.124.1.1 Temporary bonds are formed between the catalytic surface and the gas molecules.
126.96.36.199.1.1.1 These bonds hold the gas molecules in the right position on the metal surface, where they react together.
188.8.131.52.184.108.40.206 After the reaction, the N2 and CO2 products are desorbed from the surface and diffuse away from the catalytic surface.
5 Green Chemistry
5.1 using renewable resources: plant
based substances or solar energy
instead of using finite resources such
as fossil fuels, that will eventually run
5.2 companies will save money from
not having to treat hazardous
waste, or by using fewer
chemicals or less energy.
5.3 preventing any waste in the first
place, so that time and money is not
spent on cleaning up later.
5.4 maximize atom economy.
5.5 Recycling and biodegradability: At the end of
their use, materials should either be
recycled, or easily broken down in the
environment into harmless substances.