Download - The Atmosphere and Environment
Learning GoalsLearning Goals Students will describe the volume Students will describe the volume
composition of gases present in dry air composition of gases present in dry air as 79% nitrogen, 20% of oxygen and as 79% nitrogen, 20% of oxygen and the remainder being noble gases (with the remainder being noble gases (with argon as the main constituent) and argon as the main constituent) and carbon dioxide.carbon dioxide.
AirAirMixture of gasesMixture of gases
Composition of airComposition of airDry clean air :Dry clean air :
79% nitrogen79% nitrogen20% oxygen20% oxygenRemainder being noble gases Remainder being noble gases
(with (with argon as the main constituent) argon as the main constituent) and carbon dioxide and carbon dioxide
Water vapour - variableWater vapour - variable
Fractional distillation of liquid airFractional distillation of liquid air
Dust free air is pumped into the plantDust free air is pumped into the plant
Carbon dioxide is removed by bubbling through an Carbon dioxide is removed by bubbling through an alkalialkali
NaOH(aq) + CONaOH(aq) + CO22(g) (g) → → NaNa22COCO33 (aq) + H (aq) + H22O (l)O (l)
Water is removed in a drying towerWater is removed in a drying tower
Gases are compressed to 200 atmGases are compressed to 200 atm
Expansion of gasesExpansion of gases
Repeated compression and expansion of Repeated compression and expansion of gases until temperature reaches -200gases until temperature reaches -20000CC
Liquid air to a fractionating towerLiquid air to a fractionating tower
Fractional distillation of liquid airFractional distillation of liquid air
AirAir
Cooling and Cooling and compressioncompression Liquid Liquid
airair
Fractional Fractional distillationdistillation
Nitrogen Nitrogen
bp -196bp -19600CC
Argon Argon bp -186bp -18600CC
OxygenOxygen
bp -183bp -18300CC
Components of liquid air and their Components of liquid air and their boiling pointsboiling points
gas Boiling point (0C)
xenonxenon -108-108
KryptonKrypton -152-152
OxygenOxygen -183-183
ArgonArgon -186-186
NitrogenNitrogen -196-196
neonneon -246-246
heliumhelium -269-269
Laboratory Preparation of oxygenLaboratory Preparation of oxygen
water
oxygen
Hydrogen peroxide
H2O2
& MnO2
2H2H22OO22 (aq) (aq) → O→ O22 (g) + 2H (g) + 2H22O (l)O (l)
Powdered manganese (IV) oxide is used as a catalystPowdered manganese (IV) oxide is used as a catalyst
Test for Oxygen gasTest for Oxygen gas
Oxygen Oxygen gasgas
Oxygen gas relights a Oxygen gas relights a glowing glowing splint.splint.
Uses of OxygenUses of Oxygen
1. Used in cylinders for life support : Hospitals ambulances Divers (mixture of oxygen and
helium) Astronauts Passenger aircraft carry oxygen
(high altitude; air pressure low; cabin is pressurised)
Uses of OxygenUses of Oxygen
2. Rockets carry their own oxygen 2. Rockets carry their own oxygen for burning fuel; either liquid for burning fuel; either liquid oxygen or oxygen in compounds.oxygen or oxygen in compounds.
3. Making of steel – oxygen gas to 3. Making of steel – oxygen gas to burn off impuritiesburn off impurities
Uses of OxygenUses of Oxygen
4. Oxy-acetylene flame – torch to 4. Oxy-acetylene flame – torch to weld iron and steel; cut metals weld iron and steel; cut metals (3500(350000C)C)
5. Treatment of sewage – oxygen 5. Treatment of sewage – oxygen
kills harmful bacteriakills harmful bacteria
Bunsen burner flameBunsen burner flame
Pale blue flame (non-luminous):Pale blue flame (non-luminous):(Complete combustion)(Complete combustion)
CHCH44 + 2O + 2O22 → CO→ CO22 + 2H + 2H22OO
Yellow flame (luminous flame)Yellow flame (luminous flame)(Incomplete combustion)(Incomplete combustion)
2CH2CH44 + 2O + 2O22 → 2CO + 4H → 2CO + 4H22OO
CHCH44 + O + O22 → C + 2H → C + 2H22OO
Reaction of certain metals with oxygenReaction of certain metals with oxygen
ElementElement EquationEquation pH in pH in solutionsolution
potassiumpotassium 4K(s) + O4K(s) + O22(g) (g) → 2K→ 2K22O (s)O (s) 13-1413-14
sodiumsodium 4Na(s) + O4Na(s) + O22(g) (g) → 2Na→ 2Na22O(s)O(s) 13-1413-14
magnesiummagnesium 2Mg(s) + O2Mg(s) + O22(g) (g) → 2MgO(s)→ 2MgO(s) 88
ironiron 3Fe(s) + 2O3Fe(s) + 2O22(g) (g) →Fe→Fe33OO44(s)(s) insolubleinsoluble
coppercopper 2Cu(s) + O2Cu(s) + O22(g) (g) → 2CuO (s)→ 2CuO (s) insolubleinsoluble
Properties of oxide in period 3Properties of oxide in period 3
GroupGroup II IIII IIIIII IVIV VV VIVI VIIVII
ElementElement NaNa MgMg AlAl SiSi PP SS ClCl
OxideOxide NaNa22OO MgOMgO AlAl22OO33 SiOSiO22 PP22OO55 SOSO22 ClCl22OO
BondingBonding ionicionic ionicionic IonicIonic covalentcovalent covalentcovalent covalentcovalent covalentcovalent
StateState solidsolid solidsolid solidsolid solidsolid solidsolid gasgas gasgas
naturenature basicbasic basicbasic amphoteriamphotericc
acidicacidic acidicacidic acidicacidic acidicacidic
Reaction of certain non-metals with Reaction of certain non-metals with oxygenoxygen
ElementElement EquationEquation pH in pH in solutionsolution
phosphoruphosphoruss
4P(s) + 5O4P(s) + 5O22(g) (g) → 2P→ 2P22O O 55(s)(s)
phosphorus pentoxidephosphorus pentoxide
Phosphoric acid Phosphoric acid
33
sulphursulphur S(s) + OS(s) + O22(g) (g) → SO→ SO22 (g) (g) Sulphurous acidSulphurous acid
33
carboncarbon C(s) + OC(s) + O22(g) (g) → CO→ CO22 (g) (g) Carbonic acidCarbonic acid
55
Learning GoalsLearning Goals Students will name some common Students will name some common
atmospheric pollutants listed below:atmospheric pollutants listed below: carbon monoxide, methane, nitrogen carbon monoxide, methane, nitrogen
oxides (NO, NOoxides (NO, NO22), ozone, sulfur dioxide, ), ozone, sulfur dioxide,
unburnt hydrocarbonsunburnt hydrocarbons
Learning GoalsLearning Goals Students will be able to state the Students will be able to state the
sources of pollutants assources of pollutants as CO: incomplete combustion of carbon-CO: incomplete combustion of carbon-
containing substancescontaining substances Nitrogen oxides: lightning activity and Nitrogen oxides: lightning activity and
internal combustion enginesinternal combustion engines Sulfur dioxide: volcanoes and combustion Sulfur dioxide: volcanoes and combustion
of fossil fuels, containing sulfur.of fossil fuels, containing sulfur.
Air PollutionAir Pollution
What is air pollution?What is air pollution?
Air that has Air that has chemicalschemicals that harm living that harm living things or damage non-living things.things or damage non-living things.
What are air pollutants?What are air pollutants?
Solid particles and poisonous gases in Solid particles and poisonous gases in the air.the air.
Air PollutantsAir Pollutants
1. Particulates1. Particulates 2. Carbon monoxide2. Carbon monoxide
3. Oxides of nitrogen3. Oxides of nitrogen 4. Sulphur dioxide4. Sulphur dioxide
5. Ozone & CFCs5. Ozone & CFCs 6. Unburnt hydrocarbon 6. Unburnt hydrocarbon
MethaneMethane
Photochemical smogPhotochemical smog
Air pollutantsAir pollutants
SourceEffects on health and environment
Prevention
7. Carbon cycle7. Carbon cycle
8. Greenhouse gases8. Greenhouse gases
Air PollutantsAir Pollutants
SourceSource : Where does it comes from? : Where does it comes from?
EffectsEffects : How does it affect the health of : How does it affect the health of people and the environment?people and the environment?
PreventionPrevention : What measures can be taken : What measures can be taken to stop that pollutant fromto stop that pollutant from coming into the air?coming into the air?
ParticulatesParticulates
Source :Source :i.i. Ground : earth moving eqiupment, Ground : earth moving eqiupment,
construction work and windconstruction work and windii.ii. Forest fires and volcanoesForest fires and volcanoes
Effect :Effect :i.i. Irritates the lungsIrritates the lungsii.ii. Produce haze (reduce visibility)Produce haze (reduce visibility)
ParticulatesParticulates
Prevention :Prevention :
Prohibition of the use of open fires for Prohibition of the use of open fires for the disposal of domestic and the disposal of domestic and industrial wasteindustrial waste
Carbon monoxideCarbon monoxide
Source :Source :
Incomplete combustion of Incomplete combustion of fuel/petrolfuel/petrol in motor vehicle engines.in motor vehicle engines.
Effect :Effect :
i)i) DangerousDangerous – it is colourless and – it is colourless and odourless, giving no warning to its odourless, giving no warning to its presence.presence.
Carbon monoxideCarbon monoxide
Effect :Effect :
ii. ii. PoisonousPoisonous – CO is absorbed by – CO is absorbed by haemoglobin in the blood:haemoglobin in the blood:
Haemoglobin + CO Haemoglobin + CO → carboxyhaemoglobin→ carboxyhaemoglobin
This prevent the blood from This prevent the blood from transporting oxygen around the body.transporting oxygen around the body.
Carbon monoxideCarbon monoxide
Effect :Effect :iii. At lower level – it causes headaches iii. At lower level – it causes headaches
fatigue and impaired judgement.fatigue and impaired judgement.
Prevention: Prevention: Motorcars fitted with Motorcars fitted with catalytic catalytic convertersconverters. Exhaust gases pass over a . Exhaust gases pass over a platinum and rhodium catalyst.platinum and rhodium catalyst.
2CO + O2CO + O22 → 2CO→ 2CO22
Sulfur dioxideSulfur dioxide
Source :Source :
i. Burning of coal and petroleum i. Burning of coal and petroleum
(fossil fuel)(fossil fuel)
S + OS + O22 → SO→ SO22
ii. Extraction of metalsii. Extraction of metals
iii. Volcanic eruptionsiii. Volcanic eruptions
Sulfur DioxideSulfur Dioxide
Effect :Effect :i. irritates the eye and attack lungs, i. irritates the eye and attack lungs,
causing breathing difficultiescausing breathing difficultiesii. Forms acid rainii. Forms acid rain
Sulfur dioxide reacts with oxygenSulfur dioxide reacts with oxygen and water in the air to form sulfuricand water in the air to form sulfuric acidacid
2SO2SO2 2 + O+ O22 + 2H + 2H22O O → 2H→ 2H22SOSO44
SOSO22 + H + H22O → HO → H22SOSO33
Sulfur DioxideSulfur Dioxide
Effects of acid rain:Effects of acid rain:
i.i. Corrodes Corrodes limestone/marblelimestone/marble buildings buildings and metal structuresand metal structures
ii.ii. It makesIt makes waterwater in lakes and riversin lakes and rivers acidicacidic, killing fish and other aquatic , killing fish and other aquatic life.life.
iii.iii. Acidic soilAcidic soil destroys trees and other destroys trees and other vegetation.vegetation.
Sulfur dioxideSulfur dioxide
Prevention Prevention
i.i. Remove sulfur from fossil fuels Remove sulfur from fossil fuels before burningbefore burning
- too expensive and technologically difficult- too expensive and technologically difficult
ii.ii. Flue gas desulfurisationFlue gas desulfurisation
- - removal of sulfur dioxide from waste removal of sulfur dioxide from waste gasesgases
Oxides of NitrogenOxides of Nitrogen
Source: Source: Car exhaust fumesCar exhaust fumesAt high temperature (in the car engine):At high temperature (in the car engine):NN22(g) + O(g) + O22 (g) (g) → 2NO (g)→ 2NO (g)
nitric oxidenitric oxide
More oxygenMore oxygen2NO(g) + O2NO(g) + O22 (g) → 2NO (g) → 2NO22 (g) (g)
Also occur during thunderstorms (lightning) Also occur during thunderstorms (lightning) and forest fires.and forest fires.
Oxides of NitrogenOxides of Nitrogen
Effects:Effects:Forms acid rain (nitric acid)Forms acid rain (nitric acid)
4NO4NO22(g) + 2H(g) + 2H22O(g) + OO(g) + O22 (g) (g) → 4HNO→ 4HNO33(aq)(aq)
Prevention:Prevention:Motor cars are fitted with Motor cars are fitted with catalytic catalytic converterconverter on the exhaust. on the exhaust.
2NO(g) + 2CO(g) → N2NO(g) + 2CO(g) → N22 (g) + 2CO (g) + 2CO22(g)(g)
Unburnt HydrocarbonUnburnt Hydrocarbon
Source:Source:
From petrol, octane CFrom petrol, octane C88HH1818
Insufficient oxygenInsufficient oxygen present or present or
insufficient timeinsufficient time in the cylinders for all in the cylinders for all the hydrocarbons to be burnt the hydrocarbons to be burnt completelycompletely
Unburnt HydrocarbonUnburnt Hydrocarbon
Effects:Effects:
Combine with Combine with nitrogen oxidesnitrogen oxides to form to form compounds responsible for compounds responsible for photochemical smogphotochemical smog..
Prevention:Prevention:
Design engines that use more oxygen Design engines that use more oxygen for combustion of the fuels.for combustion of the fuels.
New York
Beijing
Learning GoalsLearning Goals Students will be able to describe the Students will be able to describe the
reactions in possible solutions to the reactions in possible solutions to the problems arising from some of the problems arising from some of the pollutants.pollutants. the redox reaction in catalytic converters the redox reaction in catalytic converters
to remove combustion of pollutantsto remove combustion of pollutants The use of calcium carbonate to reduce The use of calcium carbonate to reduce
the effect of acid rain and in flue gas the effect of acid rain and in flue gas desulfurisation.desulfurisation.
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
Catalytic Converters Catalytic Converters
A catalytic converter is attached to the exhaust system of a car.
It contains the catalysts platinum and rhodium.
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
Catalytic Converters Catalytic Converters
Metal- core converter
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
Catalytic Converters Catalytic Converters
Ceramic - core converter
Reactions in Catalytic ConverterReactions in Catalytic Converter
The converter uses two different types The converter uses two different types of catalysts, a of catalysts, a reductionreduction catalyst and an catalyst and an oxidizationoxidization catalyst. catalyst.
The The reduction catalyst is the first stagereduction catalyst is the first stage of the catalytic converter. of the catalytic converter. It uses platinum and rhodium to help It uses platinum and rhodium to help
reduce the NOx emissions. reduce the NOx emissions. When an NO or NOWhen an NO or NO22 molecule contacts the molecule contacts the
catalyst, the catalyst rips the nitrogen atom catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, out of the molecule and holds on to it, freeing the oxygen in the form of Ofreeing the oxygen in the form of O22. .
Reactions in Catalytic ConverterReactions in Catalytic Converter
The The oxidation catalystoxidation catalyst is the second is the second stage of the catalytic converter. It reduces stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over monoxide by burning (oxidizing) them over a platinum and palladium catalyst. a platinum and palladium catalyst.
This catalyst aids the reaction of the CO This catalyst aids the reaction of the CO and hydrocarbons with the remaining and hydrocarbons with the remaining oxygen in the exhaust gas. oxygen in the exhaust gas.
Chemical Equations in Chemical Equations in Catalytic ConverterCatalytic Converter
Word Equation:Word Equation:
Nitric oxide + carbon monoxide Nitric oxide + carbon monoxide nitrogen + carbon dioxidenitrogen + carbon dioxide
2NO (g) + 2CO (g) 2NO (g) + 2CO (g) N N22 (g) + 2CO (g) + 2CO22 (g) (g)
Word Equation:Word Equation:Octane + oxygen Octane + oxygen carbon dioxide + carbon dioxide + water vapourwater vapour
2C2C88HH1818 (g) + 25O (g) + 25O22 (g) (g) 16CO 16CO22 (g) + (g) + 18H18H22O (g)O (g)
Learning GoalsLearning Goals Students will be able to describe the Students will be able to describe the
reactions in possible solutions to the reactions in possible solutions to the problems arising from some of the problems arising from some of the pollutants.pollutants. The use of calcium carbonate to reduce The use of calcium carbonate to reduce
the effect of acid rain and in flue gas the effect of acid rain and in flue gas desulfurisation.desulfurisation.
Flue Gas DesulfurisationFlue Gas Desulfurisation
The waste gases are called flue gases. The waste gases are called flue gases.
The process of removing sulphur dioxide The process of removing sulphur dioxide from flue gases is called desulphurisation.from flue gases is called desulphurisation.
Flue Gas DesulfurisationFlue Gas Desulfurisation
1.1. CaCOCaCO33(aq) + SO(aq) + SO22 (g) (g) → CaSO→ CaSO33(s) + CO(s) + CO22 (g) (g)
The calcium sulfite is oxidised to calcium The calcium sulfite is oxidised to calcium sulfate by air.sulfate by air.
2. 2CaSO2. 2CaSO33(s) + O(s) + O22 (g) → 2CaSO (g) → 2CaSO44 (s) (s)
Calcium oxide can also be used.Calcium oxide can also be used.
CaO(s) + SOCaO(s) + SO22(g) → CaSO(g) → CaSO33 (s) (s)
Learning GoalsLearning Goals Students will discuss the Students will discuss the
importance of ozone layer importance of ozone layer andand the problems involved with the the problems involved with the
depletion of ozone by reaction with depletion of ozone by reaction with chlorine containing compounds, chlorine containing compounds, chlorofluorocarbon (CFCs)chlorofluorocarbon (CFCs)
OzoneOzoneA pale blue almost colourless gas with a A pale blue almost colourless gas with a
characteristic smellcharacteristic smell
SourceSource
- electrical machines (photocopiers)- electrical machines (photocopiers)
- photochemical reaction - photochemical reaction
(a chemical reaction that is initiated by(a chemical reaction that is initiated by
sunlight or UV light, forming sunlight or UV light, forming
photochemical smog – hazy brown photochemical smog – hazy brown
air) air)
Ozone Ozone
EffectsEffects
High altitude : protects us from harmfulHigh altitude : protects us from harmful
UVUV
Low altitude : harmful (irritates eyes, Low altitude : harmful (irritates eyes,
chest and throat)chest and throat)- Form photochemical smog:Form photochemical smog:
Ozone Ozone
EffectsEffects- Form photochemical smog:Form photochemical smog:
NONO22 (g) + O (g) + O22(g) (g) ⇋ NO(g) + O(g) + O⇋ NO(g) + O(g) + O22(g)(g)
O(g) + OO(g) + O22(g) ⇋ O(g) ⇋ O33 (g) (g)
- Ozone can further combine with - Ozone can further combine with unburnt hydrocarbon to produce unburnt hydrocarbon to produce peroxyacyl nitrates (PAN)peroxyacyl nitrates (PAN) (cause (cause tearing of the eyes)tearing of the eyes)
Chlorofluorocarbon CFCsChlorofluorocarbon CFCs
Source:Source:
- Aerosal propellants- Aerosal propellants
- Coolant fluids in refrigerators and air - Coolant fluids in refrigerators and air conditioners and conditioners and
- Making expanded polystyrene - Making expanded polystyrene packagingpackaging
Chlorofluorocarbon CFCsChlorofluorocarbon CFCs
Effects:Effects:
- - How do CFCs destroy the ozone layer?How do CFCs destroy the ozone layer?
In the presence of sunlight, CFCs In the presence of sunlight, CFCs decomposed to form decomposed to form chlorine atomschlorine atoms..
- The chlorine atoms react with ozone - The chlorine atoms react with ozone molecules to form molecules to form chlorine oxidechlorine oxide and and oxygenoxygen..
Cl + OCl + O33 → ClO + O→ ClO + O22
Ozone layerOzone layer
A thin layer of ozone in the A thin layer of ozone in the stratosphere (20-50km) acts as a stratosphere (20-50km) acts as a shieldshield, , filtering out the filtering out the harmful UV raysharmful UV rays from from the sun.the sun.
The harmful radiation causes The harmful radiation causes skin skin cancer, genetic mutationcancer, genetic mutation and and eye eye damage (cataract)damage (cataract)
Learning GoalsLearning Goals Students will be able to describe the Students will be able to describe the
carbon cycle in simple terms, to carbon cycle in simple terms, to includeinclude The processes of combustion, respiration The processes of combustion, respiration
and photosynthesisand photosynthesis How the carbon cycle regulates the How the carbon cycle regulates the
amount of carbon dioxide in the amount of carbon dioxide in the atmosphere.atmosphere.
Carbon CycleCarbon Cycle
Atmospheric carbon dioxide
respiration photosynthesisCombustion / burning of fossil fuels + volcanic activity
Learning GoalsLearning Goals Students will be able to state that Students will be able to state that
COCO22 and CH and CH44 are greenhouse gases are greenhouse gases
and and may contribute to global warming, may contribute to global warming, give the sources of these gases and give the sources of these gases and discuss possible consequences of an discuss possible consequences of an
increase in global warmingincrease in global warming
The Greenhouse EffectThe Greenhouse Effect
Greenhouse gases:Greenhouse gases:- Carbon dioxide COCarbon dioxide CO22
- Methane CHMethane CH44
- Nitrous oxide NNitrous oxide N22O O
They absorb infrared radiation and thus They absorb infrared radiation and thus reduces the amount of heat energy reduces the amount of heat energy escaping into space escaping into space : : global warming.global warming.
MethaneMethane
Source:Source:
- - Bacterial decayBacterial decay of vegetable matter of vegetable matter
trapped in low-lying wetlands and trapped in low-lying wetlands and
stagnant water.stagnant water.
- - decaying dungdecaying dung and rubbishand rubbish buried in buried in
landfillslandfills
MethaneMethane
Effects:Effects:
- - In strong sunlight,In strong sunlight, methanemethane andand unburnt hydrocarbonsunburnt hydrocarbons can react withcan react with nitrogen dioxidenitrogen dioxide to formto form photochemical photochemical smog.smog.
- - Help trap heat from the sunHelp trap heat from the sun greenhouse effectgreenhouse effect or or global warmingglobal warming..
The Greenhouse EffectThe Greenhouse Effect
Effects:Effects:
- decrease in crop yield. (areas with - decrease in crop yield. (areas with vegetation may become deserts)vegetation may become deserts)
- floods due to melting of ice in North - floods due to melting of ice in North and South poles.and South poles.
- droughts resulting in food shortage.- droughts resulting in food shortage.
Water pollutionWater pollution
- Industrial wasteIndustrial waste- Untreated sewageUntreated sewage- FertilisersFertilisers- DetergentsDetergents- Litter Litter
9. Water pollution 10. Prevention of water pollution
Prevention of Water Prevention of Water pollutionpollution
- PurificationPurification- DesalinationDesalination- New waterNew water