IB Chemistry SL Optional Topic E

Natural Sources of CO


Human Sources of CO

Oxidation of methane as plant material degrades


Natural forest fires



Incomplete combustion of fuels


Forest Fires

Methods to reduce CO

Lean burn engines- more air to insure complete oxidation of fuel


Catalytic converter


Thermal exhuast reactor- heat make CO react with more air

Natural sources of SO2
and SO3


Human sources of SO2

and SO3

Volcanic eruptions


Sea Spray


Biological Decay of organic matter containing sulfur


Reduction of Sulphates


Coal burning power stations- coal formed from decayed plant/animal material with sulfur of iron (IV) sulfide


Roasting of metal sulfides

Methods to reduce SO2 and SO3

Removal of sulphur from fuel

Use coal with low sulphur content

Use alternative sources of energy

Fluidized combustion bed- reacted with Calcium Carbonate

Alkaline scrubbing- passed through a stream of liquid with a chemical that will react with that gas. Calcium Carbonate, Magnesium Oxide, Magnesium Hydroxide.

Natural Sources of NO and NO2


Human Sources of NO and NO2

Electrical storms


Decomposition of organic matter containing nitrogen.


Nitrus oxide, formed as a result of bacteria in soil, decomposes with light.


Combustion of fossil fuels- high temperatures turn nitrogen to nitrogen dioxide


Excess use of fertilizers with nitrogen

Methods to reduce NO and NO2

Catalytic converters

Less driving

Alternative fuels


Lean burn engines- more air in the ratio of fuel to air (prone to explosions, more HC, higher temperatures means more NO)


Recirculation of exhaust gasses to cool them and reduce nitrogen oxide production

Natural Sources of Particulates


Human Sources of Particulates

Volcanic eruptions

Forest fires

Soot, Dust, Ash, Smoke


Burning of fuels

Forest fires

Industrial emissions



Methods of reducing particulates

Electrostatic precipitator- the particles are passed through an electric field and given a charge. Then the air is passed over electrodes to attract the particulates


Wet scrubbers- water spray washes particulates from exhaust gas.

Natural sources of VOCs


Human sources of VOCs

Methane-anaerobic decomposition of organic matter

Leakage from natural fossil reserves

Plants like terpenes

Natural fires


Evaporation of fuels

Partial combustion of fuels

Leakage from storage reservoirs

Extraction and transfer of petroleum

Methods for reducing VOCs

Catalytic converter- unburned hydrocarbons are oxidized into carbon dioxide and water


2 C8H18 + 25 O2 —> 16 CO2 + 18 H2O

State the equations for the production of Carbon Monoxide

2C + O2 –> 2CO


2CH4 + 3O2 –> 2CO +4H2O

State the equation for the production of sulfur dioxide and sulfur trioxide

S + O2 –> SO2


2SO2 + O2 –> 2SO3

Equation for the reaction that takes place in the Fluidized Combustion Bed

CaCO3 –> CaO + CO2


CaO + SO2 –> CaSO3

Equation for Alkaline Scrubbing
CaCO3 + SO2 –> CaSO3 + CO2
Equations for the formation of NO and NO2

O2 + N2 –> 2NO


2NO + O2 –> 2NO2




NO + O3 –> NO2 + O2




N2O –> N2 + 2NO

Why is rain water naturally acidic? (Equation)

H2O + CO2 –> H2CO3


How can coal burning contribute to acid rain? (Equation)

SO2 + H2O –> H2SO3


How does acid rain effect marble and limestone? (Equation)
CaCO3 + H2SO3 –> CaSO3 + H2O + CO2
How can Calcium Oxide neutralize acid rain? (Equation)
CaO + 2HNO2 –> Ca(NO3)2 + H2O
Catalytic Converter Equation
2NO + 2CO –> N2 + 2CO2
What are three primary pollutants produced by an automobile and how are they produced?

CO- incomplete combustion


NO- high temperatures


Hydrocarbons- evaporating unburned fuel

Lean Burn Engine Equation
2CO + O2 –> 2CO2

Equations for the:


Formation of Ozone


Depletion of Ozone

O2 + UV radiation –> 2O*


O2 + O* –> O3


O3 –> O2 + O*


O* + O3 –> 2O2

Biological Oxygen Demand
The amount of oxygen needed to decompose the organic waste at a certain temperature over a certain period of time
What would be formed when Carbon, Nitrogen, and Sulfure are decomposed by anaerobic bacteria?
Methane, Ammonia, and Hydrogen Sulfide
Why are HFCs better than CFCs?

Less reactive

Less toxic

Less flammable

Do not absorb IR radiaition

No C-Cl bonds

What are Primary, Secondary, and Tertiary pollution treatment?

Primary- Filtration of large objects


Secondary- aeration or activated sludge (getting rid of organic material using oxygen and bacteria)


Tertiary- Precipitation (removing heavy metal ions using phosphates and Ca(OH)2)

What chemicals damage the ozone layer and where do they come from?

CFCs- refridgerators, air conditioners, aerosoles


Halide compounds


Nitrogen Oxides- combustion like aircraft

How can particulates combat global warming and why doesn’t this work?

Dark colored particles absorb heat from the sun and light colored particles reflect it.


Aerosol particles do not stay in the air very long while global warming gasses can last decades.

What happens to molecules when they absorb IR radiation?
They vibrate, heating the earth.
What are important greenhouse gasses?
CO, Nitrogen Oxides, Sulfur Dioxide, and Hydrocarbons
What are the pros of distillation and osmosis?
Osmosis is cheaper, but distillation purifies water more completely.
Should ozone or chlorine be used to treat drinking water?

Chlorine is cheaper to dispose of.


Ozone is cheaper in the long run because it works 3000 times faster and is much better at disinfecting the water.

Explain the dependence of oxygen and ozone dissociation on the wavelength of the light.
The oxygen bond is stronger than the ozone bond. It needs a higher frequency wavelength to dissociate than ozone does.
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